diff --git a/compiler/testData/diagnostics/tests/ValAndFunOverrideCompatibilityClash.txt b/compiler/testData/diagnostics/tests/ValAndFunOverrideCompatibilityClash.txt
index 5c30f7f4ad2..5f75ecefbf6 100644
--- a/compiler/testData/diagnostics/tests/ValAndFunOverrideCompatibilityClash.txt
+++ b/compiler/testData/diagnostics/tests/ValAndFunOverrideCompatibilityClash.txt
@@ -31,8 +31,8 @@ public final class Foo1 : java.util.ArrayList<kotlin.Int> {
     invisible_fake open override /*1*/ /*fake_override*/ fun batchRemove(/*0*/ c: kotlin.collections.(Mutable)Collection<*>!, /*1*/ complement: kotlin.Boolean): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
-    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: kotlin.Int!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<kotlin.Int!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: kotlin.Int): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<kotlin.Int>): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun elementData(/*0*/ index: kotlin.Int): kotlin.Int!
     public open override /*1*/ /*fake_override*/ fun ensureCapacity(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun ensureCapacityInternal(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
@@ -42,21 +42,21 @@ public final class Foo1 : java.util.ArrayList<kotlin.Int> {
     public open override /*1*/ /*fake_override*/ fun get(/*0*/ index: kotlin.Int): kotlin.Int
     invisible_fake open override /*1*/ /*fake_override*/ fun grow(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: kotlin.Int!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: kotlin.Int): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.MutableIterator<kotlin.Int>
-    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: kotlin.Int!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: kotlin.Int): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.collections.MutableListIterator<kotlin.Int>
     public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.collections.MutableListIterator<kotlin.Int>
     invisible_fake open override /*1*/ /*fake_override*/ fun outOfBoundsMsg(/*0*/ index: kotlin.Int): kotlin.String!
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheck(/*0*/ index: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheckForAdd(/*0*/ index: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ s: java.io.ObjectInputStream!): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: kotlin.Int!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<kotlin.Int!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: kotlin.Int): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<kotlin.Int>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun removeAt(/*0*/ index: kotlin.Int): kotlin.Int
     protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun removeRange(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<kotlin.Int!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<kotlin.Int>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun set(/*0*/ index: kotlin.Int, /*1*/ element: kotlin.Int): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.collections.MutableList<kotlin.Int>
     public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
@@ -65,3 +65,4 @@ public final class Foo1 : java.util.ArrayList<kotlin.Int> {
     public open override /*1*/ /*fake_override*/ fun trimToSize(): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun writeObject(/*0*/ s: java.io.ObjectOutputStream!): kotlin.Unit
 }
+
diff --git a/compiler/testData/diagnostics/tests/j+k/GenericsInSupertypes.txt b/compiler/testData/diagnostics/tests/j+k/GenericsInSupertypes.txt
index 6b8f8f75cbe..eb8dedced92 100644
--- a/compiler/testData/diagnostics/tests/j+k/GenericsInSupertypes.txt
+++ b/compiler/testData/diagnostics/tests/j+k/GenericsInSupertypes.txt
@@ -13,8 +13,8 @@ public abstract class AL : java.util.ArrayList<p.P> {
     invisible_fake open override /*1*/ /*fake_override*/ fun batchRemove(/*0*/ c: kotlin.collections.(Mutable)Collection<*>!, /*1*/ complement: kotlin.Boolean): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
-    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: p.P!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<p.P!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: p.P): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<p.P>): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun elementData(/*0*/ index: kotlin.Int): p.P!
     public open override /*1*/ /*fake_override*/ fun ensureCapacity(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun ensureCapacityInternal(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
@@ -24,21 +24,21 @@ public abstract class AL : java.util.ArrayList<p.P> {
     public open override /*1*/ /*fake_override*/ fun get(/*0*/ index: kotlin.Int): p.P
     invisible_fake open override /*1*/ /*fake_override*/ fun grow(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: p.P!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: p.P): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.MutableIterator<p.P>
-    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: p.P!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: p.P): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.collections.MutableListIterator<p.P>
     public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.collections.MutableListIterator<p.P>
     invisible_fake open override /*1*/ /*fake_override*/ fun outOfBoundsMsg(/*0*/ index: kotlin.Int): kotlin.String!
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheck(/*0*/ index: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheckForAdd(/*0*/ index: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ s: java.io.ObjectInputStream!): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: p.P!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<p.P!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: p.P): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<p.P>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun removeAt(/*0*/ index: kotlin.Int): p.P
     protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun removeRange(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<p.P!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<p.P>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun set(/*0*/ index: kotlin.Int, /*1*/ element: p.P): p.P
     public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.collections.MutableList<p.P>
     public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
@@ -94,3 +94,4 @@ package p {
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
 }
+
diff --git a/compiler/testData/diagnostics/tests/j+k/specialBridges.txt b/compiler/testData/diagnostics/tests/j+k/specialBridges.txt
index aa12f176ec2..277bdf4f6b6 100644
--- a/compiler/testData/diagnostics/tests/j+k/specialBridges.txt
+++ b/compiler/testData/diagnostics/tests/j+k/specialBridges.txt
@@ -13,8 +13,8 @@ public final class B2 : java.util.ArrayList<kotlin.String>, I2 {
     invisible_fake open override /*1*/ /*fake_override*/ fun batchRemove(/*0*/ c: kotlin.collections.(Mutable)Collection<*>!, /*1*/ complement: kotlin.Boolean): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
-    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: kotlin.String!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: kotlin.String): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun elementData(/*0*/ index: kotlin.Int): kotlin.String!
     public open override /*1*/ /*fake_override*/ fun ensureCapacity(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun ensureCapacityInternal(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
@@ -24,21 +24,21 @@ public final class B2 : java.util.ArrayList<kotlin.String>, I2 {
     public open override /*1*/ /*fake_override*/ fun get(/*0*/ index: kotlin.Int): kotlin.String
     invisible_fake open override /*1*/ /*fake_override*/ fun grow(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
     public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: kotlin.String!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: kotlin.String): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.MutableIterator<kotlin.String>
-    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: kotlin.String!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: kotlin.String): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.collections.MutableListIterator<kotlin.String>
     public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.collections.MutableListIterator<kotlin.String>
     invisible_fake open override /*1*/ /*fake_override*/ fun outOfBoundsMsg(/*0*/ index: kotlin.Int): kotlin.String!
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheck(/*0*/ index: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheckForAdd(/*0*/ index: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ s: java.io.ObjectInputStream!): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: kotlin.String!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: kotlin.String): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun removeAt(/*0*/ index: kotlin.Int): kotlin.String
     protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun removeRange(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun set(/*0*/ index: kotlin.Int, /*1*/ element: kotlin.String): kotlin.String
     public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.collections.MutableList<kotlin.String>
     public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
@@ -54,3 +54,4 @@ public interface I2 {
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
+
diff --git a/compiler/testData/diagnostics/tests/platformTypes/supertypeTypeArguments.txt b/compiler/testData/diagnostics/tests/platformTypes/supertypeTypeArguments.txt
index 2dcf7cea725..17a3f88f16f 100644
--- a/compiler/testData/diagnostics/tests/platformTypes/supertypeTypeArguments.txt
+++ b/compiler/testData/diagnostics/tests/platformTypes/supertypeTypeArguments.txt
@@ -33,13 +33,13 @@ public final class HashMapEx</*0*/ K, /*1*/ V> : java.util.HashMap<K, V>, ExtMap
     invisible_fake open override /*1*/ /*fake_override*/ fun capacity(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
-    public open override /*2*/ /*fake_override*/ fun containsKey(/*0*/ key: K!): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun containsKey(/*0*/ key: K): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun containsNullValue(): kotlin.Boolean
-    public open override /*2*/ /*fake_override*/ fun containsValue(/*0*/ value: V!): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun containsValue(/*0*/ value: V): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun createEntry(/*0*/ hash: kotlin.Int, /*1*/ key: K!, /*2*/ value: V!, /*3*/ bucketIndex: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun entrySet0(): kotlin.collections.(Mutable)Set<kotlin.collections.(Mutable)Map.(Mutable)Entry<K!, V!>!>!
     public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public open override /*2*/ /*fake_override*/ fun get(/*0*/ key: K!): V?
+    public open override /*2*/ /*fake_override*/ fun get(/*0*/ key: K): V?
     invisible_fake final override /*1*/ /*fake_override*/ fun getEntry(/*0*/ key: kotlin.Any!): java.util.HashMap.Entry<K!, V!>!
     invisible_fake open override /*1*/ /*fake_override*/ fun getForNullKey(): V!
     invisible_fake final override /*1*/ /*fake_override*/ fun hash(/*0*/ k: kotlin.Any!): kotlin.Int
@@ -58,7 +58,7 @@ public final class HashMapEx</*0*/ K, /*1*/ V> : java.util.HashMap<K, V>, ExtMap
     invisible_fake open override /*1*/ /*fake_override*/ fun putForCreate(/*0*/ key: K!, /*1*/ value: V!): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun putForNullKey(/*0*/ value: V!): V!
     invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ s: java.io.ObjectInputStream!): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: K!): V?
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: K): V?
     invisible_fake final override /*1*/ /*fake_override*/ fun removeEntryForKey(/*0*/ key: kotlin.Any!): java.util.HashMap.Entry<K!, V!>!
     invisible_fake final override /*1*/ /*fake_override*/ fun removeMapping(/*0*/ o: kotlin.Any!): java.util.HashMap.Entry<K!, V!>!
     invisible_fake open override /*1*/ /*fake_override*/ fun resize(/*0*/ newCapacity: kotlin.Int): kotlin.Unit
@@ -66,3 +66,4 @@ public final class HashMapEx</*0*/ K, /*1*/ V> : java.util.HashMap<K, V>, ExtMap
     invisible_fake open override /*1*/ /*fake_override*/ fun transfer(/*0*/ newTable: kotlin.Array<(out) java.util.HashMap.Entry<(raw) kotlin.Any!, (raw) kotlin.Any!>!>!, /*1*/ rehash: kotlin.Boolean): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun writeObject(/*0*/ s: java.io.ObjectOutputStream!): kotlin.Unit
 }
+
diff --git a/compiler/testData/diagnostics/tests/scopes/visibility2.txt b/compiler/testData/diagnostics/tests/scopes/visibility2.txt
index 0479169557d..080512ea264 100644
--- a/compiler/testData/diagnostics/tests/scopes/visibility2.txt
+++ b/compiler/testData/diagnostics/tests/scopes/visibility2.txt
@@ -44,8 +44,8 @@ package b {
         invisible_fake open override /*1*/ /*fake_override*/ fun batchRemove(/*0*/ c: kotlin.collections.(Mutable)Collection<*>!, /*1*/ complement: kotlin.Boolean): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
         public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
-        public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: java.lang.Integer!): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<java.lang.Integer!>): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: java.lang.Integer): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<java.lang.Integer>): kotlin.Boolean
         invisible_fake open override /*1*/ /*fake_override*/ fun elementData(/*0*/ index: kotlin.Int): java.lang.Integer!
         public open override /*1*/ /*fake_override*/ fun ensureCapacity(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
         invisible_fake open override /*1*/ /*fake_override*/ fun ensureCapacityInternal(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
@@ -55,21 +55,21 @@ package b {
         public open override /*1*/ /*fake_override*/ fun get(/*0*/ index: kotlin.Int): java.lang.Integer
         invisible_fake open override /*1*/ /*fake_override*/ fun grow(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-        public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: java.lang.Integer!): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: java.lang.Integer): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.MutableIterator<java.lang.Integer>
-        public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: java.lang.Integer!): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: java.lang.Integer): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.collections.MutableListIterator<java.lang.Integer>
         public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.collections.MutableListIterator<java.lang.Integer>
         invisible_fake open override /*1*/ /*fake_override*/ fun outOfBoundsMsg(/*0*/ index: kotlin.Int): kotlin.String!
         invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheck(/*0*/ index: kotlin.Int): kotlin.Unit
         invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheckForAdd(/*0*/ index: kotlin.Int): kotlin.Unit
         invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ s: java.io.ObjectInputStream!): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: java.lang.Integer!): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<java.lang.Integer!>): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: java.lang.Integer): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<java.lang.Integer>): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun removeAt(/*0*/ index: kotlin.Int): java.lang.Integer
         protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun removeRange(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<java.lang.Integer!>): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<java.lang.Integer>): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun set(/*0*/ index: kotlin.Int, /*1*/ element: java.lang.Integer): java.lang.Integer
         public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.collections.MutableList<java.lang.Integer>
         public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
@@ -94,3 +94,4 @@ package b {
         }
     }
 }
+
diff --git a/compiler/testData/diagnostics/tests/subtyping/kt-1457.txt b/compiler/testData/diagnostics/tests/subtyping/kt-1457.txt
index 55a206d592b..62b3b9e8b1d 100644
--- a/compiler/testData/diagnostics/tests/subtyping/kt-1457.txt
+++ b/compiler/testData/diagnostics/tests/subtyping/kt-1457.txt
@@ -15,8 +15,8 @@ public final class MyListOfPairs</*0*/ T> : java.util.ArrayList<Pair<T, T>> {
     invisible_fake open override /*1*/ /*fake_override*/ fun batchRemove(/*0*/ c: kotlin.collections.(Mutable)Collection<*>!, /*1*/ complement: kotlin.Boolean): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
-    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: Pair<T, T>!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<Pair<T, T>!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: Pair<T, T>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<Pair<T, T>>): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun elementData(/*0*/ index: kotlin.Int): Pair<T, T>!
     public open override /*1*/ /*fake_override*/ fun ensureCapacity(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun ensureCapacityInternal(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
@@ -26,21 +26,21 @@ public final class MyListOfPairs</*0*/ T> : java.util.ArrayList<Pair<T, T>> {
     public open override /*1*/ /*fake_override*/ fun get(/*0*/ index: kotlin.Int): Pair<T, T>
     invisible_fake open override /*1*/ /*fake_override*/ fun grow(/*0*/ minCapacity: kotlin.Int): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: Pair<T, T>!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: Pair<T, T>): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.MutableIterator<Pair<T, T>>
-    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: Pair<T, T>!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: Pair<T, T>): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.collections.MutableListIterator<Pair<T, T>>
     public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.collections.MutableListIterator<Pair<T, T>>
     invisible_fake open override /*1*/ /*fake_override*/ fun outOfBoundsMsg(/*0*/ index: kotlin.Int): kotlin.String!
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheck(/*0*/ index: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheckForAdd(/*0*/ index: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ s: java.io.ObjectInputStream!): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: Pair<T, T>!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<Pair<T, T>!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: Pair<T, T>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<Pair<T, T>>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun removeAt(/*0*/ index: kotlin.Int): Pair<T, T>
     protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun removeRange(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<Pair<T, T>!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<Pair<T, T>>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun set(/*0*/ index: kotlin.Int, /*1*/ element: Pair<T, T>): Pair<T, T>
     public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.collections.MutableList<Pair<T, T>>
     public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
@@ -58,3 +58,4 @@ public final class Pair</*0*/ A, /*1*/ B> {
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
+
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/hashMapGetOrDefault.txt b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/hashMapGetOrDefault.txt
index a39ed4d04e7..01bcb449595 100644
--- a/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/hashMapGetOrDefault.txt
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/backwardCompatibility/hashMapGetOrDefault.txt
@@ -19,13 +19,13 @@ public final class MyHashMap : java.util.HashMap<kotlin.String, kotlin.String> {
     invisible_fake open override /*1*/ /*fake_override*/ fun capacity(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
-    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun containsNullValue(): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.String!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.String): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun createEntry(/*0*/ hash: kotlin.Int, /*1*/ key: kotlin.String!, /*2*/ value: kotlin.String!, /*3*/ bucketIndex: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun entrySet0(): kotlin.collections.(Mutable)Set<kotlin.collections.(Mutable)Map.(Mutable)Entry<kotlin.String!, kotlin.String!>!>!
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.String?
+    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String): kotlin.String?
     invisible_fake final override /*1*/ /*fake_override*/ fun getEntry(/*0*/ key: kotlin.Any!): java.util.HashMap.Entry<kotlin.String!, kotlin.String!>!
     invisible_fake open override /*1*/ /*fake_override*/ fun getForNullKey(): kotlin.String!
     public final fun getOrDefault(/*0*/ key: kotlin.String, /*1*/ defaultValue: kotlin.String): kotlin.String
@@ -45,7 +45,7 @@ public final class MyHashMap : java.util.HashMap<kotlin.String, kotlin.String> {
     invisible_fake open override /*1*/ /*fake_override*/ fun putForCreate(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.String!): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun putForNullKey(/*0*/ value: kotlin.String!): kotlin.String!
     invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ s: java.io.ObjectInputStream!): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!): kotlin.String?
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String): kotlin.String?
     invisible_fake final override /*1*/ /*fake_override*/ fun removeEntryForKey(/*0*/ key: kotlin.Any!): java.util.HashMap.Entry<kotlin.String!, kotlin.String!>!
     invisible_fake final override /*1*/ /*fake_override*/ fun removeMapping(/*0*/ o: kotlin.Any!): java.util.HashMap.Entry<kotlin.String!, kotlin.String!>!
     invisible_fake open override /*1*/ /*fake_override*/ fun resize(/*0*/ newCapacity: kotlin.Int): kotlin.Unit
@@ -53,3 +53,4 @@ public final class MyHashMap : java.util.HashMap<kotlin.String, kotlin.String> {
     invisible_fake open override /*1*/ /*fake_override*/ fun transfer(/*0*/ newTable: kotlin.Array<(out) java.util.HashMap.Entry<(raw) kotlin.Any!, (raw) kotlin.Any!>!>!, /*1*/ rehash: kotlin.Boolean): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun writeObject(/*0*/ s: java.io.ObjectOutputStream!): kotlin.Unit
 }
+
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/concurrentMapRemove.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/concurrentMapRemove.kt
index 31e50ed7e04..23ac45b6830 100644
--- a/compiler/testData/diagnostics/tests/targetedBuiltIns/concurrentMapRemove.kt
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/concurrentMapRemove.kt
@@ -16,6 +16,6 @@ fun foo() {
     concurrent.remove(null, null)
 
     // @PurelyImplements
-    concurrentHash.remove(null, 1)
-    concurrentHash.remove(null, null)
+    concurrentHash.remove(<!NULL_FOR_NONNULL_TYPE!>null<!>, 1)
+    concurrentHash.remove(<!NULL_FOR_NONNULL_TYPE!>null<!>, <!NULL_FOR_NONNULL_TYPE!>null<!>)
 }
diff --git a/compiler/testData/diagnostics/tests/targetedBuiltIns/mutableMapRemove.kt b/compiler/testData/diagnostics/tests/targetedBuiltIns/mutableMapRemove.kt
index a136b0dc3ef..b0a4a912026 100644
--- a/compiler/testData/diagnostics/tests/targetedBuiltIns/mutableMapRemove.kt
+++ b/compiler/testData/diagnostics/tests/targetedBuiltIns/mutableMapRemove.kt
@@ -22,7 +22,7 @@ fun foo(x: MutableMap<String, Int>, y: java.util.HashMap<String, Int>, z: java.u
 
     y.remove("", 1)
     y.remove("", <!TYPE_MISMATCH!>""<!>)
-    y.remove("", null)
+    y.remove("", <!NULL_FOR_NONNULL_TYPE!>null<!>)
 
     z.remove("", 1)
     z.remove("", <!TYPE_MISMATCH!>""<!>)
diff --git a/compiler/testData/diagnostics/testsWithStdLib/inference/kt36951.txt b/compiler/testData/diagnostics/testsWithStdLib/inference/kt36951.txt
index 7dbf51e569d..3589d3f64bf 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/inference/kt36951.txt
+++ b/compiler/testData/diagnostics/testsWithStdLib/inference/kt36951.txt
@@ -8,19 +8,20 @@ public final class Base</*0*/ T : [Error type: Cyclic upper bounds]> : kotlin.co
     public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
-    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: T!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<T!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: T): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public final fun foo(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.MutableIterator<T>
     invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ s: java.io.ObjectInputStream!): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: T!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<T!>): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<T!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: T): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
     public open override /*1*/ /*fake_override*/ fun </*0*/ T : kotlin.Any!> toArray(/*0*/ a: kotlin.Array<(out) T!>!): kotlin.Array<(out) T!>!
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     invisible_fake open override /*1*/ /*fake_override*/ fun writeObject(/*0*/ s: java.io.ObjectOutputStream!): kotlin.Unit
 }
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContains.txt b/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContains.txt
index 4c03a278a46..22104206676 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContains.txt
+++ b/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContains.txt
@@ -27,8 +27,8 @@ public final class A : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun computeIfPresent(/*0*/ p0: kotlin.String, /*1*/ p1: java.util.function.BiFunction<in kotlin.String, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun contains(/*0*/ p0: kotlin.Any!): kotlin.Boolean
     public final operator fun contains(/*0*/ x: kotlin.Char): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun elements(): java.util.Enumeration<kotlin.Int!>!
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String, in kotlin.Int>): kotlin.Unit
@@ -41,8 +41,8 @@ public final class A : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun forEachValue(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.Consumer<in kotlin.Int!>!): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun </*0*/ U : kotlin.Any!> forEachValue(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.Function<in kotlin.Int!, out U!>!, /*2*/ p2: java.util.function.Consumer<in U!>!): kotlin.Unit
     invisible_fake final override /*1*/ /*fake_override*/ fun fullAddCount(/*0*/ p0: kotlin.Long, /*1*/ p1: kotlin.Boolean): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.Int?
-    public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String!, /*1*/ defaultValue: kotlin.Int!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String): kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String, /*1*/ defaultValue: kotlin.Int): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     invisible_fake final override /*1*/ /*fake_override*/ fun helpTransfer(/*0*/ p0: kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!, /*1*/ p1: java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!): kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!
     invisible_fake final override /*1*/ /*fake_override*/ fun initTable(): kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!
@@ -75,8 +75,8 @@ public final class A : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun reduceValuesToDouble(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToDoubleFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Double, /*3*/ p3: java.util.function.DoubleBinaryOperator!): kotlin.Double
     public open override /*1*/ /*fake_override*/ fun reduceValuesToInt(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToIntFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Int, /*3*/ p3: java.util.function.IntBinaryOperator!): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun reduceValuesToLong(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToLongFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Long, /*3*/ p3: java.util.function.LongBinaryOperator!): kotlin.Long
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!): kotlin.Int?
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String): kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String, /*1*/ value: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: kotlin.String, /*1*/ p1: kotlin.Int): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: kotlin.String, /*1*/ p1: kotlin.Int, /*2*/ p2: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in kotlin.String, in kotlin.Int, out kotlin.Int>): kotlin.Unit
@@ -117,8 +117,8 @@ public final class B : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun computeIfAbsent(/*0*/ p0: kotlin.String, /*1*/ p1: java.util.function.Function<in kotlin.String, out kotlin.Int>): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun computeIfPresent(/*0*/ p0: kotlin.String, /*1*/ p1: java.util.function.BiFunction<in kotlin.String, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
     public open override /*1*/ fun contains(/*0*/ value: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun elements(): java.util.Enumeration<kotlin.Int!>!
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String, in kotlin.Int>): kotlin.Unit
@@ -131,8 +131,8 @@ public final class B : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun forEachValue(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.Consumer<in kotlin.Int!>!): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun </*0*/ U : kotlin.Any!> forEachValue(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.Function<in kotlin.Int!, out U!>!, /*2*/ p2: java.util.function.Consumer<in U!>!): kotlin.Unit
     invisible_fake final override /*1*/ /*fake_override*/ fun fullAddCount(/*0*/ p0: kotlin.Long, /*1*/ p1: kotlin.Boolean): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.Int?
-    public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String!, /*1*/ defaultValue: kotlin.Int!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String): kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String, /*1*/ defaultValue: kotlin.Int): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     invisible_fake final override /*1*/ /*fake_override*/ fun helpTransfer(/*0*/ p0: kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!, /*1*/ p1: java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!): kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!
     invisible_fake final override /*1*/ /*fake_override*/ fun initTable(): kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!
@@ -165,8 +165,8 @@ public final class B : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun reduceValuesToDouble(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToDoubleFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Double, /*3*/ p3: java.util.function.DoubleBinaryOperator!): kotlin.Double
     public open override /*1*/ /*fake_override*/ fun reduceValuesToInt(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToIntFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Int, /*3*/ p3: java.util.function.IntBinaryOperator!): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun reduceValuesToLong(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToLongFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Long, /*3*/ p3: java.util.function.LongBinaryOperator!): kotlin.Long
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!): kotlin.Int?
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String): kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String, /*1*/ value: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: kotlin.String, /*1*/ p1: kotlin.Int): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: kotlin.String, /*1*/ p1: kotlin.Int, /*2*/ p2: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in kotlin.String, in kotlin.Int, out kotlin.Int>): kotlin.Unit
@@ -207,8 +207,8 @@ public final class C : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun computeIfAbsent(/*0*/ p0: kotlin.String, /*1*/ p1: java.util.function.Function<in kotlin.String, out kotlin.Int>): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun computeIfPresent(/*0*/ p0: kotlin.String, /*1*/ p1: java.util.function.BiFunction<in kotlin.String, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
     public open override /*1*/ fun contains(/*0*/ value: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun elements(): java.util.Enumeration<kotlin.Int!>!
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String, in kotlin.Int>): kotlin.Unit
@@ -221,8 +221,8 @@ public final class C : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun forEachValue(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.Consumer<in kotlin.Int!>!): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun </*0*/ U : kotlin.Any!> forEachValue(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.Function<in kotlin.Int!, out U!>!, /*2*/ p2: java.util.function.Consumer<in U!>!): kotlin.Unit
     invisible_fake final override /*1*/ /*fake_override*/ fun fullAddCount(/*0*/ p0: kotlin.Long, /*1*/ p1: kotlin.Boolean): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.Int?
-    public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String!, /*1*/ defaultValue: kotlin.Int!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String): kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String, /*1*/ defaultValue: kotlin.Int): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     invisible_fake final override /*1*/ /*fake_override*/ fun helpTransfer(/*0*/ p0: kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!, /*1*/ p1: java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!): kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!
     invisible_fake final override /*1*/ /*fake_override*/ fun initTable(): kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!
@@ -255,8 +255,8 @@ public final class C : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun reduceValuesToDouble(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToDoubleFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Double, /*3*/ p3: java.util.function.DoubleBinaryOperator!): kotlin.Double
     public open override /*1*/ /*fake_override*/ fun reduceValuesToInt(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToIntFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Int, /*3*/ p3: java.util.function.IntBinaryOperator!): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun reduceValuesToLong(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToLongFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Long, /*3*/ p3: java.util.function.LongBinaryOperator!): kotlin.Long
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!): kotlin.Int?
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String): kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String, /*1*/ value: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: kotlin.String, /*1*/ p1: kotlin.Int): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: kotlin.String, /*1*/ p1: kotlin.Int, /*2*/ p2: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in kotlin.String, in kotlin.Int, out kotlin.Int>): kotlin.Unit
@@ -272,3 +272,4 @@ public final class C : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     invisible_fake final override /*1*/ /*fake_override*/ fun tryPresize(/*0*/ p0: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun writeObject(/*0*/ p0: java.io.ObjectOutputStream!): kotlin.Unit
 }
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContainsError.txt b/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContainsError.txt
index 4c03a278a46..22104206676 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContainsError.txt
+++ b/compiler/testData/diagnostics/testsWithStdLib/java/concurrentHashMapContainsError.txt
@@ -27,8 +27,8 @@ public final class A : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun computeIfPresent(/*0*/ p0: kotlin.String, /*1*/ p1: java.util.function.BiFunction<in kotlin.String, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun contains(/*0*/ p0: kotlin.Any!): kotlin.Boolean
     public final operator fun contains(/*0*/ x: kotlin.Char): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun elements(): java.util.Enumeration<kotlin.Int!>!
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String, in kotlin.Int>): kotlin.Unit
@@ -41,8 +41,8 @@ public final class A : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun forEachValue(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.Consumer<in kotlin.Int!>!): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun </*0*/ U : kotlin.Any!> forEachValue(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.Function<in kotlin.Int!, out U!>!, /*2*/ p2: java.util.function.Consumer<in U!>!): kotlin.Unit
     invisible_fake final override /*1*/ /*fake_override*/ fun fullAddCount(/*0*/ p0: kotlin.Long, /*1*/ p1: kotlin.Boolean): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.Int?
-    public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String!, /*1*/ defaultValue: kotlin.Int!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String): kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String, /*1*/ defaultValue: kotlin.Int): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     invisible_fake final override /*1*/ /*fake_override*/ fun helpTransfer(/*0*/ p0: kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!, /*1*/ p1: java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!): kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!
     invisible_fake final override /*1*/ /*fake_override*/ fun initTable(): kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!
@@ -75,8 +75,8 @@ public final class A : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun reduceValuesToDouble(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToDoubleFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Double, /*3*/ p3: java.util.function.DoubleBinaryOperator!): kotlin.Double
     public open override /*1*/ /*fake_override*/ fun reduceValuesToInt(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToIntFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Int, /*3*/ p3: java.util.function.IntBinaryOperator!): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun reduceValuesToLong(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToLongFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Long, /*3*/ p3: java.util.function.LongBinaryOperator!): kotlin.Long
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!): kotlin.Int?
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String): kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String, /*1*/ value: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: kotlin.String, /*1*/ p1: kotlin.Int): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: kotlin.String, /*1*/ p1: kotlin.Int, /*2*/ p2: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in kotlin.String, in kotlin.Int, out kotlin.Int>): kotlin.Unit
@@ -117,8 +117,8 @@ public final class B : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun computeIfAbsent(/*0*/ p0: kotlin.String, /*1*/ p1: java.util.function.Function<in kotlin.String, out kotlin.Int>): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun computeIfPresent(/*0*/ p0: kotlin.String, /*1*/ p1: java.util.function.BiFunction<in kotlin.String, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
     public open override /*1*/ fun contains(/*0*/ value: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun elements(): java.util.Enumeration<kotlin.Int!>!
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String, in kotlin.Int>): kotlin.Unit
@@ -131,8 +131,8 @@ public final class B : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun forEachValue(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.Consumer<in kotlin.Int!>!): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun </*0*/ U : kotlin.Any!> forEachValue(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.Function<in kotlin.Int!, out U!>!, /*2*/ p2: java.util.function.Consumer<in U!>!): kotlin.Unit
     invisible_fake final override /*1*/ /*fake_override*/ fun fullAddCount(/*0*/ p0: kotlin.Long, /*1*/ p1: kotlin.Boolean): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.Int?
-    public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String!, /*1*/ defaultValue: kotlin.Int!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String): kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String, /*1*/ defaultValue: kotlin.Int): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     invisible_fake final override /*1*/ /*fake_override*/ fun helpTransfer(/*0*/ p0: kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!, /*1*/ p1: java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!): kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!
     invisible_fake final override /*1*/ /*fake_override*/ fun initTable(): kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!
@@ -165,8 +165,8 @@ public final class B : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun reduceValuesToDouble(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToDoubleFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Double, /*3*/ p3: java.util.function.DoubleBinaryOperator!): kotlin.Double
     public open override /*1*/ /*fake_override*/ fun reduceValuesToInt(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToIntFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Int, /*3*/ p3: java.util.function.IntBinaryOperator!): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun reduceValuesToLong(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToLongFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Long, /*3*/ p3: java.util.function.LongBinaryOperator!): kotlin.Long
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!): kotlin.Int?
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String): kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String, /*1*/ value: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: kotlin.String, /*1*/ p1: kotlin.Int): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: kotlin.String, /*1*/ p1: kotlin.Int, /*2*/ p2: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in kotlin.String, in kotlin.Int, out kotlin.Int>): kotlin.Unit
@@ -207,8 +207,8 @@ public final class C : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun computeIfAbsent(/*0*/ p0: kotlin.String, /*1*/ p1: java.util.function.Function<in kotlin.String, out kotlin.Int>): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun computeIfPresent(/*0*/ p0: kotlin.String, /*1*/ p1: java.util.function.BiFunction<in kotlin.String, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
     public open override /*1*/ fun contains(/*0*/ value: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun elements(): java.util.Enumeration<kotlin.Int!>!
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String, in kotlin.Int>): kotlin.Unit
@@ -221,8 +221,8 @@ public final class C : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun forEachValue(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.Consumer<in kotlin.Int!>!): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun </*0*/ U : kotlin.Any!> forEachValue(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.Function<in kotlin.Int!, out U!>!, /*2*/ p2: java.util.function.Consumer<in U!>!): kotlin.Unit
     invisible_fake final override /*1*/ /*fake_override*/ fun fullAddCount(/*0*/ p0: kotlin.Long, /*1*/ p1: kotlin.Boolean): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.Int?
-    public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String!, /*1*/ defaultValue: kotlin.Int!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String): kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String, /*1*/ defaultValue: kotlin.Int): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     invisible_fake final override /*1*/ /*fake_override*/ fun helpTransfer(/*0*/ p0: kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!, /*1*/ p1: java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!): kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!
     invisible_fake final override /*1*/ /*fake_override*/ fun initTable(): kotlin.Array<(out) java.util.concurrent.ConcurrentHashMap.Node<kotlin.String!, kotlin.Int!>!>!
@@ -255,8 +255,8 @@ public final class C : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     public open override /*1*/ /*fake_override*/ fun reduceValuesToDouble(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToDoubleFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Double, /*3*/ p3: java.util.function.DoubleBinaryOperator!): kotlin.Double
     public open override /*1*/ /*fake_override*/ fun reduceValuesToInt(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToIntFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Int, /*3*/ p3: java.util.function.IntBinaryOperator!): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun reduceValuesToLong(/*0*/ p0: kotlin.Long, /*1*/ p1: java.util.function.ToLongFunction<in kotlin.Int!>!, /*2*/ p2: kotlin.Long, /*3*/ p3: java.util.function.LongBinaryOperator!): kotlin.Long
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!): kotlin.Int?
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String): kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String, /*1*/ value: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: kotlin.String, /*1*/ p1: kotlin.Int): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: kotlin.String, /*1*/ p1: kotlin.Int, /*2*/ p2: kotlin.Int): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in kotlin.String, in kotlin.Int, out kotlin.Int>): kotlin.Unit
@@ -272,3 +272,4 @@ public final class C : java.util.concurrent.ConcurrentHashMap<kotlin.String, kot
     invisible_fake final override /*1*/ /*fake_override*/ fun tryPresize(/*0*/ p0: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun writeObject(/*0*/ p0: java.io.ObjectOutputStream!): kotlin.Unit
 }
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableCollection.txt b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableCollection.txt
index da9b8d0e373..8b7139052df 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableCollection.txt
+++ b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableCollection.txt
@@ -9,15 +9,15 @@ public fun foo(): kotlin.Unit
     public open override /*2*/ /*fake_override*/ fun add(/*0*/ element: T): kotlin.Boolean
     public open override /*2*/ /*fake_override*/ fun addAll(/*0*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
     public open override /*2*/ /*fake_override*/ fun clear(): kotlin.Unit
-    public open override /*2*/ /*fake_override*/ fun contains(/*0*/ element: T!): kotlin.Boolean
-    public open override /*2*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<T!>): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun contains(/*0*/ element: T): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
     public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*2*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     @java.lang.Override public open override /*2*/ fun iterator(): kotlin.collections.MutableIterator<T>
-    public open override /*2*/ /*fake_override*/ fun remove(/*0*/ element: T!): kotlin.Boolean
-    public open override /*2*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<T!>): kotlin.Boolean
-    public open override /*2*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<T!>): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun remove(/*0*/ element: T): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
     public open override /*1*/ /*fake_override*/ fun </*0*/ T : kotlin.Any!> toArray(/*0*/ a: kotlin.Array<(out) T!>!): kotlin.Array<(out) T!>!
     public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
@@ -27,3 +27,4 @@ public fun foo(): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun </*0*/ T : kotlin.Any!> finishToArray(/*0*/ r: kotlin.Array<(out) T!>!, /*1*/ it: kotlin.collections.(Mutable)Iterator<*>!): kotlin.Array<(out) T!>!
     invisible_fake open override /*1*/ /*fake_override*/ fun hugeCapacity(/*0*/ minCapacity: kotlin.Int): kotlin.Int
 }
+
diff --git a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableList.txt b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableList.txt
index 03a743132f9..2932e88d173 100644
--- a/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableList.txt
+++ b/compiler/testData/diagnostics/testsWithStdLib/purelyImplementedCollection/customClassMutableList.txt
@@ -12,24 +12,24 @@ public fun foo(): kotlin.Unit
     public open override /*2*/ /*fake_override*/ fun addAll(/*0*/ index: kotlin.Int, /*1*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
     public open override /*2*/ /*fake_override*/ fun addAll(/*0*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
     public open override /*2*/ /*fake_override*/ fun clear(): kotlin.Unit
-    public open override /*2*/ /*fake_override*/ fun contains(/*0*/ element: T!): kotlin.Boolean
-    public open override /*2*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<T!>): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun contains(/*0*/ element: T): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
     public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     @java.lang.Override public open override /*2*/ fun get(/*0*/ index: kotlin.Int): T
     public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*2*/ /*fake_override*/ fun indexOf(/*0*/ element: T!): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun indexOf(/*0*/ element: T): kotlin.Int
     public open override /*2*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     public open override /*2*/ /*fake_override*/ fun iterator(): kotlin.collections.MutableIterator<T>
-    public open override /*2*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: T!): kotlin.Int
+    public open override /*2*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: T): kotlin.Int
     public open override /*2*/ /*fake_override*/ fun listIterator(): kotlin.collections.MutableListIterator<T>
     public open override /*2*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.collections.MutableListIterator<T>
     invisible_fake open override /*1*/ /*fake_override*/ fun outOfBoundsMsg(/*0*/ index: kotlin.Int): kotlin.String!
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheckForAdd(/*0*/ index: kotlin.Int): kotlin.Unit
-    public open override /*2*/ /*fake_override*/ fun remove(/*0*/ element: T!): kotlin.Boolean
-    public open override /*2*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<T!>): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun remove(/*0*/ element: T): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
     public open override /*2*/ /*fake_override*/ fun removeAt(/*0*/ index: kotlin.Int): T
     protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun removeRange(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.Unit
-    public open override /*2*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<T!>): kotlin.Boolean
+    public open override /*2*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<T>): kotlin.Boolean
     public open override /*2*/ /*fake_override*/ fun set(/*0*/ index: kotlin.Int, /*1*/ element: T): T
     public open override /*2*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.collections.MutableList<T>
     public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
@@ -41,3 +41,4 @@ public fun foo(): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun </*0*/ T : kotlin.Any!> finishToArray(/*0*/ r: kotlin.Array<(out) T!>!, /*1*/ it: kotlin.collections.(Mutable)Iterator<*>!): kotlin.Array<(out) T!>!
     invisible_fake open override /*1*/ /*fake_override*/ fun hugeCapacity(/*0*/ minCapacity: kotlin.Int): kotlin.Int
 }
+
diff --git a/compiler/testData/ir/irText/firProblems/ArrayListOverrides.ir.txt b/compiler/testData/ir/irText/firProblems/ArrayListOverrides.ir.txt
index fb74912f754..fff737ab743 100644
--- a/compiler/testData/ir/irText/firProblems/ArrayListOverrides.ir.txt
+++ b/compiler/testData/ir/irText/firProblems/ArrayListOverrides.ir.txt
@@ -36,31 +36,31 @@ FILE fqName:<root> fileName:/ArrayListOverrides.kt
       overridden:
         public open fun iterator (): @[EnhancedNullability] kotlin.collections.MutableIterator<@[EnhancedNullability] E of java.util.ArrayList> [operator] declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-    FUN FAKE_OVERRIDE name:remove visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[FlexibleNullability] kotlin.String?) returnType:kotlin.Boolean [fake_override]
+    FUN FAKE_OVERRIDE name:remove visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[EnhancedNullability] kotlin.String) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun remove (element: @[FlexibleNullability] E of java.util.ArrayList?): kotlin.Boolean declared in java.util.ArrayList
+        public open fun remove (element: @[EnhancedNullability] E of java.util.ArrayList): kotlin.Boolean declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-      VALUE_PARAMETER name:element index:0 type:@[FlexibleNullability] kotlin.String?
-    FUN FAKE_OVERRIDE name:removeAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, elements:kotlin.collections.Collection<@[FlexibleNullability] kotlin.String?>) returnType:kotlin.Boolean [fake_override]
+      VALUE_PARAMETER name:element index:0 type:@[EnhancedNullability] kotlin.String
+    FUN FAKE_OVERRIDE name:removeAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, elements:kotlin.collections.Collection<@[EnhancedNullability] kotlin.String>) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun removeAll (elements: kotlin.collections.Collection<@[FlexibleNullability] E of java.util.ArrayList?>): kotlin.Boolean declared in java.util.ArrayList
+        public open fun removeAll (elements: kotlin.collections.Collection<@[EnhancedNullability] E of java.util.ArrayList>): kotlin.Boolean declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[FlexibleNullability] kotlin.String?>
-    FUN FAKE_OVERRIDE name:retainAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, elements:kotlin.collections.Collection<@[FlexibleNullability] kotlin.String?>) returnType:kotlin.Boolean [fake_override]
+      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[EnhancedNullability] kotlin.String>
+    FUN FAKE_OVERRIDE name:retainAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, elements:kotlin.collections.Collection<@[EnhancedNullability] kotlin.String>) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun retainAll (elements: kotlin.collections.Collection<@[FlexibleNullability] E of java.util.ArrayList?>): kotlin.Boolean declared in java.util.ArrayList
+        public open fun retainAll (elements: kotlin.collections.Collection<@[EnhancedNullability] E of java.util.ArrayList>): kotlin.Boolean declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[FlexibleNullability] kotlin.String?>
-    FUN FAKE_OVERRIDE name:contains visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[FlexibleNullability] kotlin.String?) returnType:kotlin.Boolean [fake_override,operator]
+      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[EnhancedNullability] kotlin.String>
+    FUN FAKE_OVERRIDE name:contains visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[EnhancedNullability] kotlin.String) returnType:kotlin.Boolean [fake_override,operator]
       overridden:
-        public open fun contains (element: @[FlexibleNullability] E of java.util.ArrayList?): kotlin.Boolean [operator] declared in java.util.ArrayList
+        public open fun contains (element: @[EnhancedNullability] E of java.util.ArrayList): kotlin.Boolean [operator] declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-      VALUE_PARAMETER name:element index:0 type:@[FlexibleNullability] kotlin.String?
-    FUN FAKE_OVERRIDE name:containsAll visibility:public modality:OPEN <> ($this:java.util.AbstractCollection<@[FlexibleNullability] kotlin.String?>, elements:kotlin.collections.Collection<@[FlexibleNullability] kotlin.String?>) returnType:kotlin.Boolean [fake_override]
+      VALUE_PARAMETER name:element index:0 type:@[EnhancedNullability] kotlin.String
+    FUN FAKE_OVERRIDE name:containsAll visibility:public modality:OPEN <> ($this:java.util.AbstractCollection<@[FlexibleNullability] kotlin.String?>, elements:kotlin.collections.Collection<@[EnhancedNullability] kotlin.String>) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun containsAll (elements: kotlin.collections.Collection<@[FlexibleNullability] E of java.util.ArrayList?>): kotlin.Boolean [fake_override] declared in java.util.ArrayList
+        public open fun containsAll (elements: kotlin.collections.Collection<@[EnhancedNullability] E of java.util.ArrayList>): kotlin.Boolean [fake_override] declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.AbstractCollection<@[FlexibleNullability] kotlin.String?>
-      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[FlexibleNullability] kotlin.String?>
+      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[EnhancedNullability] kotlin.String>
     FUN FAKE_OVERRIDE name:isEmpty visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>) returnType:kotlin.Boolean [fake_override]
       overridden:
         public open fun isEmpty (): kotlin.Boolean declared in java.util.ArrayList
@@ -141,16 +141,16 @@ FILE fqName:<root> fileName:/ArrayListOverrides.kt
         public open fun get (index: kotlin.Int): @[EnhancedNullability] E of java.util.ArrayList [operator] declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
       VALUE_PARAMETER name:index index:0 type:kotlin.Int
-    FUN FAKE_OVERRIDE name:indexOf visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[FlexibleNullability] kotlin.String?) returnType:kotlin.Int [fake_override]
+    FUN FAKE_OVERRIDE name:indexOf visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[EnhancedNullability] kotlin.String) returnType:kotlin.Int [fake_override]
       overridden:
-        public open fun indexOf (element: @[FlexibleNullability] E of java.util.ArrayList?): kotlin.Int declared in java.util.ArrayList
+        public open fun indexOf (element: @[EnhancedNullability] E of java.util.ArrayList): kotlin.Int declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-      VALUE_PARAMETER name:element index:0 type:@[FlexibleNullability] kotlin.String?
-    FUN FAKE_OVERRIDE name:lastIndexOf visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[FlexibleNullability] kotlin.String?) returnType:kotlin.Int [fake_override]
+      VALUE_PARAMETER name:element index:0 type:@[EnhancedNullability] kotlin.String
+    FUN FAKE_OVERRIDE name:lastIndexOf visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[EnhancedNullability] kotlin.String) returnType:kotlin.Int [fake_override]
       overridden:
-        public open fun lastIndexOf (element: @[FlexibleNullability] E of java.util.ArrayList?): kotlin.Int declared in java.util.ArrayList
+        public open fun lastIndexOf (element: @[EnhancedNullability] E of java.util.ArrayList): kotlin.Int declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-      VALUE_PARAMETER name:element index:0 type:@[FlexibleNullability] kotlin.String?
+      VALUE_PARAMETER name:element index:0 type:@[EnhancedNullability] kotlin.String
     FUN FAKE_OVERRIDE name:replaceAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, p0:@[EnhancedNullability] java.util.function.UnaryOperator<@[EnhancedNullability] kotlin.String>) returnType:kotlin.Unit [fake_override]
       overridden:
         public open fun replaceAll (p0: @[EnhancedNullability] java.util.function.UnaryOperator<@[EnhancedNullability] E of java.util.ArrayList>): kotlin.Unit declared in java.util.ArrayList
@@ -200,7 +200,7 @@ FILE fqName:<root> fileName:/ArrayListOverrides.kt
         INSTANCE_INITIALIZER_CALL classDescriptor='CLASS CLASS name:A2 modality:FINAL visibility:public superTypes:[java.util.ArrayList<kotlin.String>]'
     FUN name:remove visibility:public modality:OPEN <> ($this:<root>.A2, x:kotlin.String) returnType:kotlin.Boolean
       overridden:
-        public open fun remove (element: @[FlexibleNullability] E of java.util.ArrayList?): kotlin.Boolean declared in java.util.ArrayList
+        public open fun remove (element: @[EnhancedNullability] E of java.util.ArrayList): kotlin.Boolean declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:<root>.A2
       VALUE_PARAMETER name:x index:0 type:kotlin.String
       BLOCK_BODY
@@ -236,26 +236,26 @@ FILE fqName:<root> fileName:/ArrayListOverrides.kt
       overridden:
         public open fun iterator (): @[EnhancedNullability] kotlin.collections.MutableIterator<@[EnhancedNullability] E of java.util.ArrayList> [operator] declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-    FUN FAKE_OVERRIDE name:removeAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, elements:kotlin.collections.Collection<@[FlexibleNullability] kotlin.String?>) returnType:kotlin.Boolean [fake_override]
+    FUN FAKE_OVERRIDE name:removeAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, elements:kotlin.collections.Collection<@[EnhancedNullability] kotlin.String>) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun removeAll (elements: kotlin.collections.Collection<@[FlexibleNullability] E of java.util.ArrayList?>): kotlin.Boolean declared in java.util.ArrayList
+        public open fun removeAll (elements: kotlin.collections.Collection<@[EnhancedNullability] E of java.util.ArrayList>): kotlin.Boolean declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[FlexibleNullability] kotlin.String?>
-    FUN FAKE_OVERRIDE name:retainAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, elements:kotlin.collections.Collection<@[FlexibleNullability] kotlin.String?>) returnType:kotlin.Boolean [fake_override]
+      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[EnhancedNullability] kotlin.String>
+    FUN FAKE_OVERRIDE name:retainAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, elements:kotlin.collections.Collection<@[EnhancedNullability] kotlin.String>) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun retainAll (elements: kotlin.collections.Collection<@[FlexibleNullability] E of java.util.ArrayList?>): kotlin.Boolean declared in java.util.ArrayList
+        public open fun retainAll (elements: kotlin.collections.Collection<@[EnhancedNullability] E of java.util.ArrayList>): kotlin.Boolean declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[FlexibleNullability] kotlin.String?>
-    FUN FAKE_OVERRIDE name:contains visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[FlexibleNullability] kotlin.String?) returnType:kotlin.Boolean [fake_override,operator]
+      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[EnhancedNullability] kotlin.String>
+    FUN FAKE_OVERRIDE name:contains visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[EnhancedNullability] kotlin.String) returnType:kotlin.Boolean [fake_override,operator]
       overridden:
-        public open fun contains (element: @[FlexibleNullability] E of java.util.ArrayList?): kotlin.Boolean [operator] declared in java.util.ArrayList
+        public open fun contains (element: @[EnhancedNullability] E of java.util.ArrayList): kotlin.Boolean [operator] declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-      VALUE_PARAMETER name:element index:0 type:@[FlexibleNullability] kotlin.String?
-    FUN FAKE_OVERRIDE name:containsAll visibility:public modality:OPEN <> ($this:java.util.AbstractCollection<@[FlexibleNullability] kotlin.String?>, elements:kotlin.collections.Collection<@[FlexibleNullability] kotlin.String?>) returnType:kotlin.Boolean [fake_override]
+      VALUE_PARAMETER name:element index:0 type:@[EnhancedNullability] kotlin.String
+    FUN FAKE_OVERRIDE name:containsAll visibility:public modality:OPEN <> ($this:java.util.AbstractCollection<@[FlexibleNullability] kotlin.String?>, elements:kotlin.collections.Collection<@[EnhancedNullability] kotlin.String>) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun containsAll (elements: kotlin.collections.Collection<@[FlexibleNullability] E of java.util.ArrayList?>): kotlin.Boolean [fake_override] declared in java.util.ArrayList
+        public open fun containsAll (elements: kotlin.collections.Collection<@[EnhancedNullability] E of java.util.ArrayList>): kotlin.Boolean [fake_override] declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.AbstractCollection<@[FlexibleNullability] kotlin.String?>
-      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[FlexibleNullability] kotlin.String?>
+      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[EnhancedNullability] kotlin.String>
     FUN FAKE_OVERRIDE name:isEmpty visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>) returnType:kotlin.Boolean [fake_override]
       overridden:
         public open fun isEmpty (): kotlin.Boolean declared in java.util.ArrayList
@@ -336,16 +336,16 @@ FILE fqName:<root> fileName:/ArrayListOverrides.kt
         public open fun get (index: kotlin.Int): @[EnhancedNullability] E of java.util.ArrayList [operator] declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
       VALUE_PARAMETER name:index index:0 type:kotlin.Int
-    FUN FAKE_OVERRIDE name:indexOf visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[FlexibleNullability] kotlin.String?) returnType:kotlin.Int [fake_override]
+    FUN FAKE_OVERRIDE name:indexOf visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[EnhancedNullability] kotlin.String) returnType:kotlin.Int [fake_override]
       overridden:
-        public open fun indexOf (element: @[FlexibleNullability] E of java.util.ArrayList?): kotlin.Int declared in java.util.ArrayList
+        public open fun indexOf (element: @[EnhancedNullability] E of java.util.ArrayList): kotlin.Int declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-      VALUE_PARAMETER name:element index:0 type:@[FlexibleNullability] kotlin.String?
-    FUN FAKE_OVERRIDE name:lastIndexOf visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[FlexibleNullability] kotlin.String?) returnType:kotlin.Int [fake_override]
+      VALUE_PARAMETER name:element index:0 type:@[EnhancedNullability] kotlin.String
+    FUN FAKE_OVERRIDE name:lastIndexOf visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, element:@[EnhancedNullability] kotlin.String) returnType:kotlin.Int [fake_override]
       overridden:
-        public open fun lastIndexOf (element: @[FlexibleNullability] E of java.util.ArrayList?): kotlin.Int declared in java.util.ArrayList
+        public open fun lastIndexOf (element: @[EnhancedNullability] E of java.util.ArrayList): kotlin.Int declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<kotlin.String>
-      VALUE_PARAMETER name:element index:0 type:@[FlexibleNullability] kotlin.String?
+      VALUE_PARAMETER name:element index:0 type:@[EnhancedNullability] kotlin.String
     FUN FAKE_OVERRIDE name:replaceAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<kotlin.String>, p0:@[EnhancedNullability] java.util.function.UnaryOperator<@[EnhancedNullability] kotlin.String>) returnType:kotlin.Unit [fake_override]
       overridden:
         public open fun replaceAll (p0: @[EnhancedNullability] java.util.function.UnaryOperator<@[EnhancedNullability] E of java.util.ArrayList>): kotlin.Unit declared in java.util.ArrayList
diff --git a/compiler/testData/ir/irText/firProblems/ClashResolutionDescriptor.ir.txt b/compiler/testData/ir/irText/firProblems/ClashResolutionDescriptor.ir.txt
index edb47c7fdcb..0aa801514a8 100644
--- a/compiler/testData/ir/irText/firProblems/ClashResolutionDescriptor.ir.txt
+++ b/compiler/testData/ir/irText/firProblems/ClashResolutionDescriptor.ir.txt
@@ -153,7 +153,7 @@ FILE fqName:<root> fileName:/ClashResolutionDescriptor.kt
                 BLOCK type=kotlin.collections.Collection<<root>.ComponentDescriptor> origin=ELVIS
                   VAR IR_TEMPORARY_VARIABLE name:tmp_1 type:kotlin.collections.Collection<<root>.ComponentDescriptor>? [val]
                     TYPE_OP type=kotlin.collections.Collection<<root>.ComponentDescriptor>? origin=SAFE_CAST typeOperand=kotlin.collections.Collection<<root>.ComponentDescriptor>
-                      CALL 'public open fun get (key: @[FlexibleNullability] K of java.util.HashMap?): @[EnhancedNullability] V of java.util.HashMap? [operator] declared in java.util.HashMap' type=@[EnhancedNullability] kotlin.Any? origin=GET_ARRAY_ELEMENT
+                      CALL 'public open fun get (key: @[EnhancedNullability] K of java.util.HashMap): @[EnhancedNullability] V of java.util.HashMap? [operator] declared in java.util.HashMap' type=@[EnhancedNullability] kotlin.Any? origin=GET_ARRAY_ELEMENT
                         $this: CALL 'private final fun <get-registrationMap> (): java.util.HashMap<java.lang.reflect.Type, kotlin.Any>{ kotlin.collections.TypeAliasesKt.HashMap<java.lang.reflect.Type, kotlin.Any> } declared in <root>' type=java.util.HashMap<java.lang.reflect.Type, kotlin.Any>{ kotlin.collections.TypeAliasesKt.HashMap<java.lang.reflect.Type, kotlin.Any> } origin=GET_PROPERTY
                         key: CALL 'public final fun <get-applicableTo> (): java.lang.Class<E of <root>.PlatformExtensionsClashResolver> declared in <root>.PlatformExtensionsClashResolver' type=java.lang.Class<out <root>.PlatformSpecificExtension<*>> origin=GET_PROPERTY
                           $this: GET_VAR 'val resolver: <root>.PlatformExtensionsClashResolver<*> [val] declared in <root>.resolveClashesIfAny' type=<root>.PlatformExtensionsClashResolver<*> origin=null
diff --git a/compiler/testData/ir/irText/firProblems/MultiList.ir.txt b/compiler/testData/ir/irText/firProblems/MultiList.ir.txt
index aed310849ce..5fb5efa0b39 100644
--- a/compiler/testData/ir/irText/firProblems/MultiList.ir.txt
+++ b/compiler/testData/ir/irText/firProblems/MultiList.ir.txt
@@ -209,13 +209,13 @@ FILE fqName:<root> fileName:/MultiList.kt
     FUN FAKE_OVERRIDE name:contains visibility:public modality:OPEN <> ($this:kotlin.collections.List<<root>.Some<T of <root>.SomeList>>, element:<root>.Some<T of <root>.SomeList>) returnType:kotlin.Boolean [fake_override,operator]
       overridden:
         public abstract fun contains (element: <root>.Some<T of <root>.MyList>): kotlin.Boolean [fake_override,operator] declared in <root>.MyList
-        public open fun contains (element: @[FlexibleNullability] E of java.util.ArrayList?): kotlin.Boolean [operator] declared in java.util.ArrayList
+        public open fun contains (element: @[EnhancedNullability] E of java.util.ArrayList): kotlin.Boolean [operator] declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:kotlin.collections.List<<root>.Some<T of <root>.SomeList>>
       VALUE_PARAMETER name:element index:0 type:<root>.Some<T of <root>.SomeList>
     FUN FAKE_OVERRIDE name:containsAll visibility:public modality:OPEN <> ($this:kotlin.collections.List<<root>.Some<T of <root>.SomeList>>, elements:kotlin.collections.Collection<<root>.Some<T of <root>.SomeList>>) returnType:kotlin.Boolean [fake_override]
       overridden:
         public abstract fun containsAll (elements: kotlin.collections.Collection<<root>.Some<T of <root>.MyList>>): kotlin.Boolean [fake_override] declared in <root>.MyList
-        public open fun containsAll (elements: kotlin.collections.Collection<@[FlexibleNullability] E of java.util.ArrayList?>): kotlin.Boolean [fake_override] declared in java.util.ArrayList
+        public open fun containsAll (elements: kotlin.collections.Collection<@[EnhancedNullability] E of java.util.ArrayList>): kotlin.Boolean [fake_override] declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:kotlin.collections.List<<root>.Some<T of <root>.SomeList>>
       VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<<root>.Some<T of <root>.SomeList>>
     FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator]
@@ -244,7 +244,7 @@ FILE fqName:<root> fileName:/MultiList.kt
     FUN FAKE_OVERRIDE name:indexOf visibility:public modality:OPEN <> ($this:kotlin.collections.List<<root>.Some<T of <root>.SomeList>>, element:<root>.Some<T of <root>.SomeList>) returnType:kotlin.Int [fake_override]
       overridden:
         public abstract fun indexOf (element: <root>.Some<T of <root>.MyList>): kotlin.Int [fake_override] declared in <root>.MyList
-        public open fun indexOf (element: @[FlexibleNullability] E of java.util.ArrayList?): kotlin.Int declared in java.util.ArrayList
+        public open fun indexOf (element: @[EnhancedNullability] E of java.util.ArrayList): kotlin.Int declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:kotlin.collections.List<<root>.Some<T of <root>.SomeList>>
       VALUE_PARAMETER name:element index:0 type:<root>.Some<T of <root>.SomeList>
     FUN FAKE_OVERRIDE name:isEmpty visibility:public modality:OPEN <> ($this:kotlin.collections.List<<root>.Some<T of <root>.SomeList>>) returnType:kotlin.Boolean [fake_override]
@@ -260,7 +260,7 @@ FILE fqName:<root> fileName:/MultiList.kt
     FUN FAKE_OVERRIDE name:lastIndexOf visibility:public modality:OPEN <> ($this:kotlin.collections.List<<root>.Some<T of <root>.SomeList>>, element:<root>.Some<T of <root>.SomeList>) returnType:kotlin.Int [fake_override]
       overridden:
         public abstract fun lastIndexOf (element: <root>.Some<T of <root>.MyList>): kotlin.Int [fake_override] declared in <root>.MyList
-        public open fun lastIndexOf (element: @[FlexibleNullability] E of java.util.ArrayList?): kotlin.Int declared in java.util.ArrayList
+        public open fun lastIndexOf (element: @[EnhancedNullability] E of java.util.ArrayList): kotlin.Int declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:kotlin.collections.List<<root>.Some<T of <root>.SomeList>>
       VALUE_PARAMETER name:element index:0 type:<root>.Some<T of <root>.SomeList>
     FUN FAKE_OVERRIDE name:listIterator visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<T of <root>.SomeList>>) returnType:@[EnhancedNullability] kotlin.collections.MutableListIterator<@[EnhancedNullability] <root>.Some<T of <root>.SomeList>> [fake_override]
@@ -327,21 +327,21 @@ FILE fqName:<root> fileName:/MultiList.kt
       overridden:
         public open fun clear (): kotlin.Unit declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<<root>.Some<T of <root>.SomeList>>
-    FUN FAKE_OVERRIDE name:remove visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<T of <root>.SomeList>>, element:@[FlexibleNullability] <root>.Some<T of <root>.SomeList>?) returnType:kotlin.Boolean [fake_override]
+    FUN FAKE_OVERRIDE name:remove visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<T of <root>.SomeList>>, element:@[EnhancedNullability] <root>.Some<T of <root>.SomeList>) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun remove (element: @[FlexibleNullability] E of java.util.ArrayList?): kotlin.Boolean declared in java.util.ArrayList
+        public open fun remove (element: @[EnhancedNullability] E of java.util.ArrayList): kotlin.Boolean declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<<root>.Some<T of <root>.SomeList>>
-      VALUE_PARAMETER name:element index:0 type:@[FlexibleNullability] <root>.Some<T of <root>.SomeList>?
-    FUN FAKE_OVERRIDE name:removeAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<T of <root>.SomeList>>, elements:kotlin.collections.Collection<@[FlexibleNullability] <root>.Some<T of <root>.SomeList>?>) returnType:kotlin.Boolean [fake_override]
+      VALUE_PARAMETER name:element index:0 type:@[EnhancedNullability] <root>.Some<T of <root>.SomeList>
+    FUN FAKE_OVERRIDE name:removeAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<T of <root>.SomeList>>, elements:kotlin.collections.Collection<@[EnhancedNullability] <root>.Some<T of <root>.SomeList>>) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun removeAll (elements: kotlin.collections.Collection<@[FlexibleNullability] E of java.util.ArrayList?>): kotlin.Boolean declared in java.util.ArrayList
+        public open fun removeAll (elements: kotlin.collections.Collection<@[EnhancedNullability] E of java.util.ArrayList>): kotlin.Boolean declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<<root>.Some<T of <root>.SomeList>>
-      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[FlexibleNullability] <root>.Some<T of <root>.SomeList>?>
-    FUN FAKE_OVERRIDE name:retainAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<T of <root>.SomeList>>, elements:kotlin.collections.Collection<@[FlexibleNullability] <root>.Some<T of <root>.SomeList>?>) returnType:kotlin.Boolean [fake_override]
+      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[EnhancedNullability] <root>.Some<T of <root>.SomeList>>
+    FUN FAKE_OVERRIDE name:retainAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<T of <root>.SomeList>>, elements:kotlin.collections.Collection<@[EnhancedNullability] <root>.Some<T of <root>.SomeList>>) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun retainAll (elements: kotlin.collections.Collection<@[FlexibleNullability] E of java.util.ArrayList?>): kotlin.Boolean declared in java.util.ArrayList
+        public open fun retainAll (elements: kotlin.collections.Collection<@[EnhancedNullability] E of java.util.ArrayList>): kotlin.Boolean declared in java.util.ArrayList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<<root>.Some<T of <root>.SomeList>>
-      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[FlexibleNullability] <root>.Some<T of <root>.SomeList>?>
+      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[EnhancedNullability] <root>.Some<T of <root>.SomeList>>
     FUN FAKE_OVERRIDE name:toArray visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<T of <root>.SomeList>>) returnType:@[FlexibleNullability] kotlin.Array<out @[FlexibleNullability] kotlin.Any?>? [fake_override]
       overridden:
         public open fun toArray (): @[FlexibleNullability] kotlin.Array<out @[FlexibleNullability] kotlin.Any?>? declared in java.util.ArrayList
@@ -519,21 +519,21 @@ FILE fqName:<root> fileName:/MultiList.kt
       overridden:
         public open fun clear (): kotlin.Unit [fake_override] declared in <root>.SomeList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<<root>.Some<kotlin.String>>
-    FUN FAKE_OVERRIDE name:remove visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<kotlin.String>>, element:@[FlexibleNullability] <root>.Some<kotlin.String>?) returnType:kotlin.Boolean [fake_override]
+    FUN FAKE_OVERRIDE name:remove visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<kotlin.String>>, element:@[EnhancedNullability] <root>.Some<kotlin.String>) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun remove (element: @[FlexibleNullability] <root>.Some<T of <root>.SomeList>?): kotlin.Boolean [fake_override] declared in <root>.SomeList
+        public open fun remove (element: @[EnhancedNullability] <root>.Some<T of <root>.SomeList>): kotlin.Boolean [fake_override] declared in <root>.SomeList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<<root>.Some<kotlin.String>>
-      VALUE_PARAMETER name:element index:0 type:@[FlexibleNullability] <root>.Some<kotlin.String>?
-    FUN FAKE_OVERRIDE name:removeAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<kotlin.String>>, elements:kotlin.collections.Collection<@[FlexibleNullability] <root>.Some<kotlin.String>?>) returnType:kotlin.Boolean [fake_override]
+      VALUE_PARAMETER name:element index:0 type:@[EnhancedNullability] <root>.Some<kotlin.String>
+    FUN FAKE_OVERRIDE name:removeAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<kotlin.String>>, elements:kotlin.collections.Collection<@[EnhancedNullability] <root>.Some<kotlin.String>>) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun removeAll (elements: kotlin.collections.Collection<@[FlexibleNullability] <root>.Some<T of <root>.SomeList>?>): kotlin.Boolean [fake_override] declared in <root>.SomeList
+        public open fun removeAll (elements: kotlin.collections.Collection<@[EnhancedNullability] <root>.Some<T of <root>.SomeList>>): kotlin.Boolean [fake_override] declared in <root>.SomeList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<<root>.Some<kotlin.String>>
-      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[FlexibleNullability] <root>.Some<kotlin.String>?>
-    FUN FAKE_OVERRIDE name:retainAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<kotlin.String>>, elements:kotlin.collections.Collection<@[FlexibleNullability] <root>.Some<kotlin.String>?>) returnType:kotlin.Boolean [fake_override]
+      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[EnhancedNullability] <root>.Some<kotlin.String>>
+    FUN FAKE_OVERRIDE name:retainAll visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<kotlin.String>>, elements:kotlin.collections.Collection<@[EnhancedNullability] <root>.Some<kotlin.String>>) returnType:kotlin.Boolean [fake_override]
       overridden:
-        public open fun retainAll (elements: kotlin.collections.Collection<@[FlexibleNullability] <root>.Some<T of <root>.SomeList>?>): kotlin.Boolean [fake_override] declared in <root>.SomeList
+        public open fun retainAll (elements: kotlin.collections.Collection<@[EnhancedNullability] <root>.Some<T of <root>.SomeList>>): kotlin.Boolean [fake_override] declared in <root>.SomeList
       $this: VALUE_PARAMETER name:<this> type:java.util.ArrayList<<root>.Some<kotlin.String>>
-      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[FlexibleNullability] <root>.Some<kotlin.String>?>
+      VALUE_PARAMETER name:elements index:0 type:kotlin.collections.Collection<@[EnhancedNullability] <root>.Some<kotlin.String>>
     FUN FAKE_OVERRIDE name:toArray visibility:public modality:OPEN <> ($this:java.util.ArrayList<<root>.Some<kotlin.String>>) returnType:@[FlexibleNullability] kotlin.Array<out @[FlexibleNullability] kotlin.Any?>? [fake_override]
       overridden:
         public open fun toArray (): @[FlexibleNullability] kotlin.Array<out @[FlexibleNullability] kotlin.Any?>? [fake_override] declared in <root>.SomeList
diff --git a/compiler/testData/loadJava/compiledKotlin/platformTypes/notnullTypeArgument.javac.txt b/compiler/testData/loadJava/compiledKotlin/platformTypes/notnullTypeArgument.javac.txt
index 6e6ae8ec45a..5bf719d197e 100644
--- a/compiler/testData/loadJava/compiledKotlin/platformTypes/notnullTypeArgument.javac.txt
+++ b/compiler/testData/loadJava/compiledKotlin/platformTypes/notnullTypeArgument.javac.txt
@@ -14,8 +14,8 @@ public final class C : java.util.ArrayList<kotlin.String> {
     invisible_fake open override /*1*/ /*fake_override*/ fun batchRemove(/*0*/ p0: kotlin.collections.(Mutable)Collection<*>!, /*1*/ p1: kotlin.Boolean): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
-    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: kotlin.String!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: kotlin.String): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun elementData(/*0*/ p0: kotlin.Int): kotlin.String!
     public open override /*1*/ /*fake_override*/ fun ensureCapacity(/*0*/ p0: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun ensureCapacityInternal(/*0*/ p0: kotlin.Int): kotlin.Unit
@@ -24,10 +24,10 @@ public final class C : java.util.ArrayList<kotlin.String> {
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.Consumer<in kotlin.String!>!): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun get(/*0*/ index: kotlin.Int): kotlin.String
     invisible_fake open override /*1*/ /*fake_override*/ fun grow(/*0*/ p0: kotlin.Int): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: kotlin.String!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: kotlin.String): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.MutableIterator<kotlin.String>
-    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: kotlin.String!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: kotlin.String): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.collections.MutableListIterator<kotlin.String>
     public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.collections.MutableListIterator<kotlin.String>
     invisible_fake open override /*1*/ /*fake_override*/ fun outOfBoundsMsg(/*0*/ p0: kotlin.Int): kotlin.String!
@@ -35,13 +35,13 @@ public final class C : java.util.ArrayList<kotlin.String> {
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheck(/*0*/ p0: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheckForAdd(/*0*/ p0: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ p0: java.io.ObjectInputStream!): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: kotlin.String!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: kotlin.String): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun removeAt(/*0*/ p0: kotlin.Int): kotlin.String
     public open override /*1*/ /*fake_override*/ fun removeIf(/*0*/ p0: java.util.function.Predicate<in kotlin.String>): kotlin.Boolean
     protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun removeRange(/*0*/ p0: kotlin.Int, /*1*/ p1: kotlin.Int): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.UnaryOperator<kotlin.String>): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun set(/*0*/ index: kotlin.Int, /*1*/ element: kotlin.String): kotlin.String
     public open override /*1*/ /*fake_override*/ /*isHiddenForResolutionEverywhereBesideSupercalls*/ fun sort(/*0*/ p0: java.util.Comparator<in kotlin.String!>!): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.String!>
diff --git a/compiler/testData/loadJava/compiledKotlin/platformTypes/notnullTypeArgument.txt b/compiler/testData/loadJava/compiledKotlin/platformTypes/notnullTypeArgument.txt
index 78a35a571c6..e014541e3fd 100644
--- a/compiler/testData/loadJava/compiledKotlin/platformTypes/notnullTypeArgument.txt
+++ b/compiler/testData/loadJava/compiledKotlin/platformTypes/notnullTypeArgument.txt
@@ -14,8 +14,8 @@ public final class C : java.util.ArrayList<kotlin.String> {
     invisible_fake open override /*1*/ /*fake_override*/ fun batchRemove(/*0*/ p0: kotlin.collections.(Mutable)Collection<*>!, /*1*/ p1: kotlin.Boolean): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
-    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: kotlin.String!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ element: kotlin.String): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun elementData(/*0*/ p0: kotlin.Int): kotlin.String!
     public open override /*1*/ /*fake_override*/ fun ensureCapacity(/*0*/ p0: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun ensureCapacityInternal(/*0*/ p0: kotlin.Int): kotlin.Unit
@@ -23,21 +23,21 @@ public final class C : java.util.ArrayList<kotlin.String> {
     invisible_fake open override /*1*/ /*fake_override*/ fun fastRemove(/*0*/ p0: kotlin.Int): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun get(/*0*/ index: kotlin.Int): kotlin.String
     invisible_fake open override /*1*/ /*fake_override*/ fun grow(/*0*/ p0: kotlin.Int): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: kotlin.String!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ element: kotlin.String): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.MutableIterator<kotlin.String>
-    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: kotlin.String!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: kotlin.String): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.collections.MutableListIterator<kotlin.String>
     public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.collections.MutableListIterator<kotlin.String>
     invisible_fake open override /*1*/ /*fake_override*/ fun outOfBoundsMsg(/*0*/ p0: kotlin.Int): kotlin.String!
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheck(/*0*/ p0: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun rangeCheckForAdd(/*0*/ p0: kotlin.Int): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ p0: java.io.ObjectInputStream!): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: kotlin.String!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ element: kotlin.String): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun removeAt(/*0*/ p0: kotlin.Int): kotlin.String
     protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun removeRange(/*0*/ p0: kotlin.Int, /*1*/ p1: kotlin.Int): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun set(/*0*/ index: kotlin.Int, /*1*/ element: kotlin.String): kotlin.String
     public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.collections.MutableList<kotlin.String>
     public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
diff --git a/compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt b/compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt
index a4386b84f55..46cfd364a9d 100644
--- a/compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt
+++ b/compiler/util/src/org/jetbrains/kotlin/config/LanguageVersionSettings.kt
@@ -254,7 +254,6 @@ enum class LanguageFeature(
     ProhibitNonExhaustiveIfInRhsOfElvis(KOTLIN_1_8, kind = BUG_FIX), // KT-44705
     ProhibitAccessToEnumCompanionMembersInEnumConstructorCall(KOTLIN_1_8, kind = BUG_FIX), // KT-49110
     ReportMissingUpperBoundsViolatedErrorOnAbbreviationAtSupertypes(KOTLIN_1_8, kind = BUG_FIX), // KT-29168
-    IgnoreNullabilityForErasedValueParameters(KOTLIN_1_8, kind = BUG_FIX),
     ForbidUsingExtensionPropertyTypeParameterInDelegate(KOTLIN_1_8, kind = BUG_FIX),
     SynchronizedSuspendError(KOTLIN_1_8),
     ReportNonVarargSpreadOnGenericCalls(KOTLIN_1_8, kind = BUG_FIX), // KT-48162
@@ -285,6 +284,9 @@ enum class LanguageFeature(
     EnumEntries(KOTLIN_1_9, sinceApiVersion = ApiVersion.KOTLIN_1_8, defaultState = State.DISABLED, kind = UNSTABLE_FEATURE), // KT-48872
     EnableDfaWarningsInK2(KOTLIN_1_9, kind = OTHER), // KT-50965
 
+    // Disabled for indefinite time. See KT-53751
+    IgnoreNullabilityForErasedValueParameters(sinceVersion = null, kind = BUG_FIX),
+
     // Disabled for indefinite time. See KT-48535 and related discussion
     ApproximateIntegerLiteralTypesInReceiverPosition(sinceVersion = null),