diff --git a/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.txt b/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.txt
index 6cd3c885d45..4e261e98d7d 100644
--- a/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.txt
+++ b/compiler/testData/diagnostics/tests/TraitOverrideObjectMethods.txt
@@ -2,7 +2,7 @@ package
 
 internal interface MyTrait : java.lang.Object {
     protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any!
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public abstract override /*1*/ fun finalize(): kotlin.Unit
     public final override /*1*/ /*fake_override*/ fun getClass(): java.lang.Class<*>!
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
diff --git a/compiler/testData/diagnostics/tests/ValAndFunOverrideCompatibilityClash.txt b/compiler/testData/diagnostics/tests/ValAndFunOverrideCompatibilityClash.txt
index 7aa796b4868..b9509423bbb 100644
--- a/compiler/testData/diagnostics/tests/ValAndFunOverrideCompatibilityClash.txt
+++ b/compiler/testData/diagnostics/tests/ValAndFunOverrideCompatibilityClash.txt
@@ -25,12 +25,12 @@ internal final class Foo1 : java.util.ArrayList<kotlin.Int> {
     invisible_fake final override /*1*/ /*fake_override*/ var size: kotlin.Int
     public open override /*1*/ /*fake_override*/ fun add(/*0*/ index: kotlin.Int, /*1*/ element: kotlin.Int!): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun add(/*0*/ e: kotlin.Int!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ c: (kotlin.MutableCollection<out kotlin.Int!>..kotlin.Collection<kotlin.Int!>?)): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ index: kotlin.Int, /*1*/ c: (kotlin.MutableCollection<out kotlin.Int!>..kotlin.Collection<kotlin.Int!>?)): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ c: kotlin.Collection<kotlin.Int!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ index: kotlin.Int, /*1*/ c: kotlin.Collection<kotlin.Int!>): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun batchRemove(/*0*/ p0: kotlin.(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*/ o: kotlin.Any!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
+    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ o: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ c: kotlin.Collection<kotlin.Any?>): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun elementData(/*0*/ p0: kotlin.Int): kotlin.Int!
     public open override /*1*/ /*fake_override*/ fun ensureCapacity(/*0*/ p0: kotlin.Int): kotlin.Unit
@@ -40,24 +40,24 @@ internal 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*/ p0: kotlin.Int): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ o: kotlin.Any!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ o: kotlin.Any?): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.(Mutable)Iterator<kotlin.Int!>!
-    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ o: kotlin.Any!): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.(Mutable)ListIterator<kotlin.Int!>!
-    public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.(Mutable)ListIterator<kotlin.Int!>!
+    public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.MutableIterator<kotlin.Int!>
+    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ o: kotlin.Any?): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.MutableListIterator<kotlin.Int!>
+    public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.MutableListIterator<kotlin.Int!>
     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*/ o: kotlin.Any!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ o: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun remove(/*0*/ index: kotlin.Int): kotlin.Int!
-    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ c: kotlin.(Mutable)Collection<*>!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ c: kotlin.Collection<*>): 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 retainAll(/*0*/ c: kotlin.(Mutable)Collection<*>!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ c: kotlin.Collection<*>): 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 size(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.(Mutable)List<kotlin.Int!>!
+    public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.MutableList<kotlin.Int!>
     public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
     public open override /*1*/ /*fake_override*/ fun </*0*/ T> toArray(/*0*/ p0: kotlin.Array<(out) T!>!): kotlin.Array<(out) T!>!
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
diff --git a/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.txt b/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.txt
index 18399c5fefe..6ba09e9a8d9 100644
--- a/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.txt
+++ b/compiler/testData/diagnostics/tests/delegation/DelegationToJavaIface.txt
@@ -11,13 +11,13 @@ internal final class TestIface : java.lang.Runnable {
 internal final class TestObject : java.lang.Object {
     public constructor TestObject(/*0*/ o: java.lang.Object)
     protected open override /*1*/ /*delegation*/ fun clone(): kotlin.Any!
-    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     protected open override /*1*/ /*delegation*/ fun finalize(): kotlin.Unit
     public final override /*1*/ /*fake_override*/ fun getClass(): java.lang.Class<*>!
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public final override /*1*/ /*fake_override*/ fun notify(): kotlin.Unit
     public final override /*1*/ /*fake_override*/ fun notifyAll(): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String!
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     public final override /*1*/ /*fake_override*/ fun wait(): kotlin.Unit
     public final override /*1*/ /*fake_override*/ fun wait(/*0*/ p0: kotlin.Long): kotlin.Unit
     public final override /*1*/ /*fake_override*/ fun wait(/*0*/ p0: kotlin.Long, /*1*/ p1: kotlin.Int): kotlin.Unit
diff --git a/compiler/testData/diagnostics/tests/j+k/GenericsInSupertypes.txt b/compiler/testData/diagnostics/tests/j+k/GenericsInSupertypes.txt
index 0d49eb4bc2f..f3be5c0cf91 100644
--- a/compiler/testData/diagnostics/tests/j+k/GenericsInSupertypes.txt
+++ b/compiler/testData/diagnostics/tests/j+k/GenericsInSupertypes.txt
@@ -7,12 +7,12 @@ internal abstract class AL : java.util.ArrayList<p.P> {
     invisible_fake final override /*1*/ /*fake_override*/ var size: kotlin.Int
     public open override /*1*/ /*fake_override*/ fun add(/*0*/ index: kotlin.Int, /*1*/ element: p.P!): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun add(/*0*/ e: p.P!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ c: (kotlin.MutableCollection<out p.P!>..kotlin.Collection<p.P!>?)): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ index: kotlin.Int, /*1*/ c: (kotlin.MutableCollection<out p.P!>..kotlin.Collection<p.P!>?)): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ c: kotlin.Collection<p.P!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ index: kotlin.Int, /*1*/ c: kotlin.Collection<p.P!>): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun batchRemove(/*0*/ p0: kotlin.(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*/ o: kotlin.Any!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
+    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ o: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ c: kotlin.Collection<kotlin.Any?>): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun elementData(/*0*/ p0: kotlin.Int): p.P!
     public open override /*1*/ /*fake_override*/ fun ensureCapacity(/*0*/ p0: kotlin.Int): kotlin.Unit
@@ -22,24 +22,24 @@ internal 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*/ p0: kotlin.Int): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ o: kotlin.Any!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ o: kotlin.Any?): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.(Mutable)Iterator<p.P!>!
-    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ o: kotlin.Any!): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.(Mutable)ListIterator<p.P!>!
-    public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.(Mutable)ListIterator<p.P!>!
+    public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.MutableIterator<p.P!>
+    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ o: kotlin.Any?): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.MutableListIterator<p.P!>
+    public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.MutableListIterator<p.P!>
     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*/ o: kotlin.Any!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ o: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun remove(/*0*/ index: kotlin.Int): p.P!
-    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ c: kotlin.(Mutable)Collection<*>!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ c: kotlin.Collection<*>): 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 retainAll(/*0*/ c: kotlin.(Mutable)Collection<*>!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ c: kotlin.Collection<*>): 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 size(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.(Mutable)List<p.P!>!
+    public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.MutableList<p.P!>
     public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
     public open override /*1*/ /*fake_override*/ fun </*0*/ T> toArray(/*0*/ p0: kotlin.Array<(out) T!>!): kotlin.Array<(out) T!>!
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
@@ -50,7 +50,7 @@ internal abstract class AL : java.util.ArrayList<p.P> {
 internal abstract class K : p.C<p.P> {
     public constructor K()
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun foo(/*0*/ p: p.A<p.P!>!): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun foo(/*0*/ p: p.A<p.P!>): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
@@ -67,7 +67,7 @@ package p {
     public open class B</*0*/ TB> : p.A<TB!> {
         public constructor B</*0*/ TB>()
         public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-        public/*package*/ open override /*1*/ fun foo(/*0*/ p: p.A<TB!>!): kotlin.Unit
+        public/*package*/ open override /*1*/ fun foo(/*0*/ p: p.A<TB!>): kotlin.Unit
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     }
@@ -75,7 +75,7 @@ package p {
     public open class C</*0*/ TC> : p.B<TC!>, p.A<TC!> {
         public constructor C</*0*/ TC>()
         public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-        public open override /*2*/ /*fake_override*/ fun foo(/*0*/ p: p.A<TC!>!): kotlin.Unit
+        public open override /*2*/ /*fake_override*/ fun foo(/*0*/ p: p.A<TC!>): kotlin.Unit
         public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
         public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
     }
diff --git a/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-SpecialTypes.txt b/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-SpecialTypes.txt
index ac3d083dfb6..04ca74d4447 100644
--- a/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-SpecialTypes.txt
+++ b/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-SpecialTypes.txt
@@ -11,9 +11,9 @@ public open class A {
 
 public open class X</*0*/ T> {
     public constructor X</*0*/ T>()
-    public/*package*/ open fun barN(/*0*/ org.jetbrains.annotations.NotNull() a: T!): kotlin.Unit
+    public/*package*/ open fun barN(/*0*/ org.jetbrains.annotations.NotNull() a: T): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    org.jetbrains.annotations.NotNull() public/*package*/ open fun fooN(): T!
+    org.jetbrains.annotations.NotNull() public/*package*/ open fun fooN(): T
     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/j+k/SupertypeArgumentsNullability-NotNull-UserTypes.txt b/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-UserTypes.txt
index 28891f6e92d..0363db8ebbb 100644
--- a/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-UserTypes.txt
+++ b/compiler/testData/diagnostics/tests/j+k/SupertypeArgumentsNullability-NotNull-UserTypes.txt
@@ -11,9 +11,9 @@ public open class A {
 
 public open class X</*0*/ T> {
     public constructor X</*0*/ T>()
-    public/*package*/ open fun barN(/*0*/ org.jetbrains.annotations.NotNull() a: T!): kotlin.Unit
+    public/*package*/ open fun barN(/*0*/ org.jetbrains.annotations.NotNull() a: T): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
-    org.jetbrains.annotations.NotNull() public/*package*/ open fun fooN(): T!
+    org.jetbrains.annotations.NotNull() public/*package*/ open fun fooN(): T
     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/j+k/javaStaticImport.txt b/compiler/testData/diagnostics/tests/j+k/javaStaticImport.txt
index 6a1ca31528e..a508a227198 100644
--- a/compiler/testData/diagnostics/tests/j+k/javaStaticImport.txt
+++ b/compiler/testData/diagnostics/tests/j+k/javaStaticImport.txt
@@ -19,7 +19,7 @@ package backend {
             public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 
             // Static members
-            org.jetbrains.annotations.NotNull() public open fun doSmth(/*0*/ s: kotlin.String!): kotlin.String!
+            org.jetbrains.annotations.NotNull() public open fun doSmth(/*0*/ s: kotlin.String!): kotlin.String
         }
     }
 }
diff --git a/compiler/testData/diagnostics/tests/j+k/kt1730_implementCharSequence.txt b/compiler/testData/diagnostics/tests/j+k/kt1730_implementCharSequence.txt
index 437a3bf71db..8b782e8a748 100644
--- a/compiler/testData/diagnostics/tests/j+k/kt1730_implementCharSequence.txt
+++ b/compiler/testData/diagnostics/tests/j+k/kt1730_implementCharSequence.txt
@@ -6,8 +6,8 @@ public open class C : kotlin.CharSequence {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     java.lang.Override() public open override /*1*/ fun length(): kotlin.Int
-    java.lang.Override() public open override /*1*/ fun subSequence(/*0*/ start: kotlin.Int, /*1*/ end: kotlin.Int): kotlin.CharSequence!
-    java.lang.Override() public open override /*1*/ fun toString(): kotlin.String!
+    java.lang.Override() public open override /*1*/ fun subSequence(/*0*/ start: kotlin.Int, /*1*/ end: kotlin.Int): kotlin.CharSequence
+    java.lang.Override() public open override /*1*/ fun toString(): kotlin.String
 }
 
 internal final class T : C {
@@ -16,6 +16,6 @@ internal final class T : C {
     public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     java.lang.Override() public open override /*1*/ /*fake_override*/ fun length(): kotlin.Int
-    java.lang.Override() public open override /*1*/ /*fake_override*/ fun subSequence(/*0*/ start: kotlin.Int, /*1*/ end: kotlin.Int): kotlin.CharSequence!
-    java.lang.Override() public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String!
+    java.lang.Override() public open override /*1*/ /*fake_override*/ fun subSequence(/*0*/ start: kotlin.Int, /*1*/ end: kotlin.Int): kotlin.CharSequence
+    java.lang.Override() public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
diff --git a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1270.kt b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1270.kt
index 3b0a1227122..7f56511c759 100644
--- a/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1270.kt
+++ b/compiler/testData/diagnostics/tests/nullabilityAndSmartCasts/kt1270.kt
@@ -5,7 +5,7 @@ package kt1270
 
 fun foo() {
     val sc = java.util.HashMap<String, SomeClass>()[""]
-    val value = sc.value
+    val value = sc<!UNSAFE_CALL!>.<!>value
 }
 
 private class SomeClass() {
diff --git a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/kt6829.kt b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/kt6829.kt
index 9d76a42b010..04c35b7a7ba 100644
--- a/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/kt6829.kt
+++ b/compiler/testData/diagnostics/tests/platformTypes/nullabilityWarnings/kt6829.kt
@@ -16,7 +16,7 @@ public class J {
 
 fun foo(collection: Collection<J>) {
     val mapped = collection.map { it.method() }
-    <!NULLABILITY_MISMATCH_BASED_ON_JAVA_ANNOTATIONS!>mapped[0]<!>.length()
+    mapped[0]<!UNSAFE_CALL!>.<!>length()
 }
 
 public fun <T, R> Iterable<T>.map(transform: (T) -> R): List<R> {
diff --git a/compiler/testData/diagnostics/tests/platformTypes/supertypeTypeArguments.txt b/compiler/testData/diagnostics/tests/platformTypes/supertypeTypeArguments.txt
index f8e286d2825..63e5756d6bc 100644
--- a/compiler/testData/diagnostics/tests/platformTypes/supertypeTypeArguments.txt
+++ b/compiler/testData/diagnostics/tests/platformTypes/supertypeTypeArguments.txt
@@ -29,12 +29,12 @@ internal final class HashMapEx</*0*/ K, /*1*/ V> : java.util.HashMap<K, V>, ExtM
     invisible_fake open override /*1*/ /*fake_override*/ fun addEntry(/*0*/ p0: kotlin.Int, /*1*/ p1: K!, /*2*/ p2: V!, /*3*/ p3: kotlin.Int): kotlin.Unit
     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 clone(): kotlin.Any
     public open override /*2*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.Any?): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun containsNullValue(): kotlin.Boolean
     public open override /*2*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Any?): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun createEntry(/*0*/ p0: kotlin.Int, /*1*/ p1: K!, /*2*/ p2: V!, /*3*/ p3: kotlin.Int): kotlin.Unit
-    public open override /*2*/ /*fake_override*/ fun entrySet(): kotlin.Set<kotlin.Map.Entry<K, V>>
+    public open override /*2*/ /*fake_override*/ fun entrySet(): kotlin.MutableSet<kotlin.MutableMap.MutableEntry<K!, V!>>
     invisible_fake open override /*1*/ /*fake_override*/ fun entrySet0(): kotlin.(Mutable)Set<kotlin.(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: kotlin.Any?): V?
@@ -44,24 +44,24 @@ internal final class HashMapEx</*0*/ K, /*1*/ V> : java.util.HashMap<K, V>, ExtM
     public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
     invisible_fake open override /*1*/ /*fake_override*/ fun init(): kotlin.Unit
     public open override /*2*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-    public open override /*2*/ /*fake_override*/ fun keySet(): kotlin.Set<K>
+    public open override /*2*/ /*fake_override*/ fun keySet(): kotlin.MutableSet<K!>
     invisible_fake open override /*1*/ /*fake_override*/ fun loadFactor(): kotlin.Float
     invisible_fake open override /*1*/ /*fake_override*/ fun newEntryIterator(): kotlin.(Mutable)Iterator<kotlin.(Mutable)Map.(Mutable)Entry<K!, V!>!>!
     invisible_fake open override /*1*/ /*fake_override*/ fun newKeyIterator(): kotlin.(Mutable)Iterator<K!>!
     invisible_fake open override /*1*/ /*fake_override*/ fun newValueIterator(): kotlin.(Mutable)Iterator<V!>!
-    public open override /*1*/ /*fake_override*/ fun put(/*0*/ key: K!, /*1*/ value: V!): V!
-    public open override /*1*/ /*fake_override*/ fun putAll(/*0*/ m: (kotlin.MutableMap<out K!, out V!>..kotlin.Map<out K!, V!>?)): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun put(/*0*/ key: K!, /*1*/ value: V!): V?
+    public open override /*1*/ /*fake_override*/ fun putAll(/*0*/ m: kotlin.Map<out K!, V!>): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun putAllForCreate(/*0*/ p0: (kotlin.MutableMap<out K!, out V!>..kotlin.Map<out K!, V!>?)): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun putForCreate(/*0*/ p0: K!, /*1*/ p1: V!): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun putForNullKey(/*0*/ p0: V!): V!
     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*/ key: kotlin.Any!): V!
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.Any?): V?
     invisible_fake final override /*1*/ /*fake_override*/ fun removeEntryForKey(/*0*/ p0: kotlin.Any!): java.util.HashMap.Entry<K!, V!>!
     invisible_fake final override /*1*/ /*fake_override*/ fun removeMapping(/*0*/ p0: kotlin.Any!): java.util.HashMap.Entry<K!, V!>!
     invisible_fake open override /*1*/ /*fake_override*/ fun resize(/*0*/ p0: kotlin.Int): kotlin.Unit
     public open override /*2*/ /*fake_override*/ fun size(): kotlin.Int
     public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
     invisible_fake open override /*1*/ /*fake_override*/ fun transfer(/*0*/ p0: kotlin.Array<(out) java.util.HashMap.Entry<*, *>!>!, /*1*/ p1: kotlin.Boolean): kotlin.Unit
-    public open override /*2*/ /*fake_override*/ fun values(): kotlin.Collection<V>
+    public open override /*2*/ /*fake_override*/ fun values(): kotlin.MutableCollection<V!>
     invisible_fake open override /*1*/ /*fake_override*/ fun writeObject(/*0*/ p0: java.io.ObjectOutputStream!): kotlin.Unit
 }
diff --git a/compiler/testData/diagnostics/tests/regressions/kt1639-JFrame.txt b/compiler/testData/diagnostics/tests/regressions/kt1639-JFrame.txt
index c78ad5184f8..6463448f65c 100644
--- a/compiler/testData/diagnostics/tests/regressions/kt1639-JFrame.txt
+++ b/compiler/testData/diagnostics/tests/regressions/kt1639-JFrame.txt
@@ -645,7 +645,7 @@ package test {
         invisible_fake final override /*1*/ /*fake_override*/ fun toBack_NoClientCode(): kotlin.Unit
         public open override /*1*/ /*fake_override*/ fun toFront(): kotlin.Unit
         invisible_fake final override /*1*/ /*fake_override*/ fun toFront_NoClientCode(): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String!
+        public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
         public open override /*1*/ /*fake_override*/ fun transferFocus(): kotlin.Unit
         invisible_fake open override /*1*/ /*fake_override*/ fun transferFocus(/*0*/ p0: kotlin.Boolean): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun transferFocusBackward(): kotlin.Unit
diff --git a/compiler/testData/diagnostics/tests/regressions/kt588.txt b/compiler/testData/diagnostics/tests/regressions/kt588.txt
index a6169143ac2..2cb6a33a6f2 100644
--- a/compiler/testData/diagnostics/tests/regressions/kt588.txt
+++ b/compiler/testData/diagnostics/tests/regressions/kt588.txt
@@ -69,7 +69,7 @@ internal final class Test : java.lang.Thread {
     invisible_fake open override /*1*/ /*fake_override*/ fun stop0(/*0*/ p0: kotlin.Any!): kotlin.Unit
     kotlin.deprecated(value = "Deprecated in Java") public final override /*1*/ /*fake_override*/ fun suspend(): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun suspend0(): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String!
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 
     public companion object Companion {
         private constructor Companion()
diff --git a/compiler/testData/diagnostics/tests/scopes/visibility2.txt b/compiler/testData/diagnostics/tests/scopes/visibility2.txt
index db6469ade5f..c7e4aa9e390 100644
--- a/compiler/testData/diagnostics/tests/scopes/visibility2.txt
+++ b/compiler/testData/diagnostics/tests/scopes/visibility2.txt
@@ -38,12 +38,12 @@ package b {
         invisible_fake final override /*1*/ /*fake_override*/ var size: kotlin.Int
         public open override /*1*/ /*fake_override*/ fun add(/*0*/ e: java.lang.Integer!): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun add(/*0*/ index: kotlin.Int, /*1*/ element: java.lang.Integer!): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ c: (kotlin.MutableCollection<out java.lang.Integer!>..kotlin.Collection<java.lang.Integer!>?)): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ index: kotlin.Int, /*1*/ c: (kotlin.MutableCollection<out java.lang.Integer!>..kotlin.Collection<java.lang.Integer!>?)): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ c: kotlin.Collection<java.lang.Integer!>): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ index: kotlin.Int, /*1*/ c: kotlin.Collection<java.lang.Integer!>): kotlin.Boolean
         invisible_fake open override /*1*/ /*fake_override*/ fun batchRemove(/*0*/ p0: kotlin.(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*/ o: kotlin.Any!): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
+        public open override /*1*/ /*fake_override*/ fun contains(/*0*/ o: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ c: kotlin.Collection<kotlin.Any?>): kotlin.Boolean
         invisible_fake open override /*1*/ /*fake_override*/ fun elementData(/*0*/ p0: kotlin.Int): java.lang.Integer!
         public open override /*1*/ /*fake_override*/ fun ensureCapacity(/*0*/ p0: kotlin.Int): kotlin.Unit
@@ -53,24 +53,24 @@ 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*/ p0: kotlin.Int): kotlin.Unit
         public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-        public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ o: kotlin.Any!): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ o: kotlin.Any?): kotlin.Int
         public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.(Mutable)Iterator<java.lang.Integer!>!
-        public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ o: kotlin.Any!): kotlin.Int
-        public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.(Mutable)ListIterator<java.lang.Integer!>!
-        public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.(Mutable)ListIterator<java.lang.Integer!>!
+        public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.MutableIterator<java.lang.Integer!>
+        public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ o: kotlin.Any?): kotlin.Int
+        public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.MutableListIterator<java.lang.Integer!>
+        public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.MutableListIterator<java.lang.Integer!>
         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*/ o: kotlin.Any!): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun remove(/*0*/ o: kotlin.Any?): kotlin.Boolean
         public open override /*1*/ /*fake_override*/ fun remove(/*0*/ index: kotlin.Int): java.lang.Integer!
-        public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ c: kotlin.(Mutable)Collection<*>!): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ c: kotlin.Collection<*>): 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 retainAll(/*0*/ c: kotlin.(Mutable)Collection<*>!): kotlin.Boolean
+        public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ c: kotlin.Collection<*>): 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 size(): kotlin.Int
-        public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.(Mutable)List<java.lang.Integer!>!
+        public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.MutableList<java.lang.Integer!>
         public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
         public open override /*1*/ /*fake_override*/ fun </*0*/ T> toArray(/*0*/ p0: kotlin.Array<(out) T!>!): kotlin.Array<(out) T!>!
         public open override /*1*/ fun toString(): kotlin.String
diff --git a/compiler/testData/diagnostics/tests/subtyping/kt-1457.txt b/compiler/testData/diagnostics/tests/subtyping/kt-1457.txt
index 49c11b0035e..3ec3dd40f8f 100644
--- a/compiler/testData/diagnostics/tests/subtyping/kt-1457.txt
+++ b/compiler/testData/diagnostics/tests/subtyping/kt-1457.txt
@@ -9,12 +9,12 @@ internal final class MyListOfPairs</*0*/ T> : java.util.ArrayList<Pair<T, T>> {
     invisible_fake final override /*1*/ /*fake_override*/ var size: kotlin.Int
     public open override /*1*/ /*fake_override*/ fun add(/*0*/ e: Pair<T, T>!): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun add(/*0*/ index: kotlin.Int, /*1*/ element: Pair<T, T>!): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ c: (kotlin.MutableCollection<out Pair<T, T>!>..kotlin.Collection<Pair<T, T>!>?)): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ index: kotlin.Int, /*1*/ c: (kotlin.MutableCollection<out Pair<T, T>!>..kotlin.Collection<Pair<T, T>!>?)): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ c: kotlin.Collection<Pair<T, T>!>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun addAll(/*0*/ index: kotlin.Int, /*1*/ c: kotlin.Collection<Pair<T, T>!>): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun batchRemove(/*0*/ p0: kotlin.(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*/ o: kotlin.Any!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
+    public open override /*1*/ /*fake_override*/ fun contains(/*0*/ o: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun containsAll(/*0*/ c: kotlin.Collection<kotlin.Any?>): kotlin.Boolean
     invisible_fake open override /*1*/ /*fake_override*/ fun elementData(/*0*/ p0: kotlin.Int): Pair<T, T>!
     public open override /*1*/ /*fake_override*/ fun ensureCapacity(/*0*/ p0: kotlin.Int): kotlin.Unit
@@ -24,24 +24,24 @@ internal 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*/ p0: kotlin.Int): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ o: kotlin.Any!): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun indexOf(/*0*/ o: kotlin.Any?): kotlin.Int
     public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.(Mutable)Iterator<Pair<T, T>!>!
-    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ o: kotlin.Any!): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.(Mutable)ListIterator<Pair<T, T>!>!
-    public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.(Mutable)ListIterator<Pair<T, T>!>!
+    public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.MutableIterator<Pair<T, T>!>
+    public open override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ o: kotlin.Any?): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun listIterator(): kotlin.MutableListIterator<Pair<T, T>!>
+    public open override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.MutableListIterator<Pair<T, T>!>
     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*/ o: kotlin.Any!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun remove(/*0*/ o: kotlin.Any?): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun remove(/*0*/ index: kotlin.Int): Pair<T, T>!
-    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ c: kotlin.(Mutable)Collection<*>!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun removeAll(/*0*/ c: kotlin.Collection<*>): 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 retainAll(/*0*/ c: kotlin.(Mutable)Collection<*>!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun retainAll(/*0*/ c: kotlin.Collection<*>): 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 size(): kotlin.Int
-    public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.(Mutable)List<Pair<T, T>!>!
+    public open override /*1*/ /*fake_override*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.MutableList<Pair<T, T>!>
     public open override /*1*/ /*fake_override*/ fun toArray(): kotlin.Array<(out) kotlin.Any!>!
     public open override /*1*/ /*fake_override*/ fun </*0*/ T> toArray(/*0*/ p0: kotlin.Array<(out) T!>!): kotlin.Array<(out) T!>!
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
diff --git a/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumAnnotated.txt b/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumAnnotated.txt
index 0f5c9acb5f8..a8a18e3895f 100644
--- a/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumAnnotated.txt
+++ b/compiler/testData/diagnostics/tests/when/ExhaustivePlatformEnumAnnotated.txt
@@ -32,7 +32,7 @@ public final enum class J : kotlin.Enum<J!> {
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 
     // Static members
-    org.jetbrains.annotations.NotNull() public open fun create(): J!
+    org.jetbrains.annotations.NotNull() public open fun create(): J
     public final /*synthesized*/ fun valueOf(/*0*/ value: kotlin.String): J
     public final /*synthesized*/ fun values(): kotlin.Array<J>
 }