diff --git a/compiler/testData/builtin-classes/java8/kotlin-collections.txt b/compiler/testData/builtin-classes/java8/kotlin-collections.txt
index 58ccca8500e..a06b9f98a21 100644
--- a/compiler/testData/builtin-classes/java8/kotlin-collections.txt
+++ b/compiler/testData/builtin-classes/java8/kotlin-collections.txt
@@ -32,9 +32,9 @@ public interface Collection</*0*/ out E> : kotlin.collections.Iterable<E> {
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.Consumer<in E!>!): kotlin.Unit
     public abstract fun isEmpty(): kotlin.Boolean
     public abstract override /*1*/ fun iterator(): kotlin.collections.Iterator<E>
-    public open fun parallelStream(): java.util.stream.Stream<@kotlin.UnsafeVariance E!>!
-    public open override /*1*/ fun spliterator(): java.util.Spliterator<@kotlin.UnsafeVariance E!>!
-    public open fun stream(): java.util.stream.Stream<@kotlin.UnsafeVariance E!>!
+    public open fun parallelStream(): java.util.stream.Stream<@kotlin.UnsafeVariance E>
+    public open override /*1*/ fun spliterator(): java.util.Spliterator<@kotlin.UnsafeVariance E!>
+    public open fun stream(): java.util.stream.Stream<@kotlin.UnsafeVariance E>
 }
 
 public abstract class DoubleIterator : kotlin.collections.Iterator<kotlin.Double> {
@@ -64,7 +64,7 @@ public abstract class IntIterator : kotlin.collections.Iterator<kotlin.Int> {
 public interface Iterable</*0*/ out T> {
     public open fun forEach(/*0*/ p0: java.util.function.Consumer<in T!>!): kotlin.Unit
     public abstract operator fun iterator(): kotlin.collections.Iterator<T>
-    public open fun spliterator(): java.util.Spliterator<@kotlin.UnsafeVariance T!>!
+    public open fun spliterator(): java.util.Spliterator<@kotlin.UnsafeVariance T>
 }
 
 public interface Iterator</*0*/ out T> {
@@ -86,9 +86,9 @@ public interface List</*0*/ out E> : kotlin.collections.Collection<E> {
     public abstract fun lastIndexOf(/*0*/ element: @kotlin.UnsafeVariance E): kotlin.Int
     public abstract fun listIterator(): kotlin.collections.ListIterator<E>
     public abstract fun listIterator(/*0*/ index: kotlin.Int): kotlin.collections.ListIterator<E>
-    public open override /*1*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<E!>!
-    public open override /*1*/ fun spliterator(): java.util.Spliterator<@kotlin.UnsafeVariance E!>!
-    public open override /*1*/ /*fake_override*/ fun stream(): java.util.stream.Stream<E!>!
+    public open override /*1*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<E>
+    public open override /*1*/ fun spliterator(): java.util.Spliterator<@kotlin.UnsafeVariance E!>
+    public open override /*1*/ /*fake_override*/ fun stream(): java.util.stream.Stream<E>
     public abstract fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.collections.List<E>
 }
 
@@ -121,7 +121,7 @@ public interface Map</*0*/ K, /*1*/ out V> {
         public abstract fun <get-values>(): kotlin.collections.Collection<V>
     public abstract fun containsKey(/*0*/ key: K): kotlin.Boolean
     public abstract fun containsValue(/*0*/ value: @kotlin.UnsafeVariance V): kotlin.Boolean
-    public open fun forEach(/*0*/ p0: java.util.function.BiConsumer<in K!, in V!>!): kotlin.Unit
+    public open fun forEach(/*0*/ p0: java.util.function.BiConsumer<in K, in V>): kotlin.Unit
     public abstract operator fun get(/*0*/ key: K): V?
     @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open fun getOrDefault(/*0*/ key: K, /*1*/ defaultValue: @kotlin.UnsafeVariance V): V
     public abstract fun isEmpty(): kotlin.Boolean
@@ -145,19 +145,19 @@ public interface MutableCollection</*0*/ E> : kotlin.collections.Collection<E>,
     public open override /*2*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.Consumer<in E!>!): kotlin.Unit
     public abstract override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     public abstract override /*2*/ fun iterator(): kotlin.collections.MutableIterator<E>
-    public open override /*1*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<E!>!
+    public open override /*1*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<E>
     public abstract fun remove(/*0*/ element: E): kotlin.Boolean
     public abstract fun removeAll(/*0*/ elements: kotlin.collections.Collection<E>): kotlin.Boolean
-    public open fun removeIf(/*0*/ p0: java.util.function.Predicate<in E!>!): kotlin.Boolean
+    public open fun removeIf(/*0*/ p0: java.util.function.Predicate<in E>): kotlin.Boolean
     public abstract fun retainAll(/*0*/ elements: kotlin.collections.Collection<E>): kotlin.Boolean
-    public open override /*2*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<E!>!
-    public open override /*1*/ /*fake_override*/ fun stream(): java.util.stream.Stream<E!>!
+    public open override /*2*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<E!>
+    public open override /*1*/ /*fake_override*/ fun stream(): java.util.stream.Stream<E>
 }
 
 public interface MutableIterable</*0*/ out T> : kotlin.collections.Iterable<T> {
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.Consumer<in T!>!): kotlin.Unit
     public abstract override /*1*/ fun iterator(): kotlin.collections.MutableIterator<T>
-    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<T!>!
+    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<T>
 }
 
 public interface MutableIterator</*0*/ out T> : kotlin.collections.Iterator<T> {
@@ -185,17 +185,17 @@ public interface MutableList</*0*/ E> : kotlin.collections.List<E>, kotlin.colle
     public abstract override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: E): kotlin.Int
     public abstract override /*1*/ fun listIterator(): kotlin.collections.MutableListIterator<E>
     public abstract override /*1*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.collections.MutableListIterator<E>
-    public open override /*2*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<E!>!
+    public open override /*2*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<E>
     public abstract override /*1*/ fun remove(/*0*/ element: E): kotlin.Boolean
     public abstract override /*1*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<E>): kotlin.Boolean
     public abstract fun removeAt(/*0*/ index: kotlin.Int): E
-    public open override /*1*/ /*fake_override*/ fun removeIf(/*0*/ p0: java.util.function.Predicate<in E!>!): kotlin.Boolean
-    public open fun replaceAll(/*0*/ p0: java.util.function.UnaryOperator<E!>!): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun removeIf(/*0*/ p0: java.util.function.Predicate<in E>): kotlin.Boolean
+    public open fun replaceAll(/*0*/ p0: java.util.function.UnaryOperator<E>): kotlin.Unit
     public abstract override /*1*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<E>): kotlin.Boolean
     public abstract operator fun set(/*0*/ index: kotlin.Int, /*1*/ element: E): E
     public open /*isHiddenForResolutionEverywhereBesideSupercalls*/ fun sort(/*0*/ p0: java.util.Comparator<in E!>!): kotlin.Unit
-    public open override /*2*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<E!>!
-    public open override /*2*/ /*fake_override*/ fun stream(): java.util.stream.Stream<E!>!
+    public open override /*2*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<E!>
+    public open override /*2*/ /*fake_override*/ fun stream(): java.util.stream.Stream<E>
     public abstract override /*1*/ fun subList(/*0*/ fromIndex: kotlin.Int, /*1*/ toIndex: kotlin.Int): kotlin.collections.MutableList<E>
 }
 
@@ -222,24 +222,24 @@ public interface MutableMap</*0*/ K, /*1*/ V> : kotlin.collections.Map<K, V> {
     public abstract override /*1*/ val values: kotlin.collections.MutableCollection<V>
         public abstract override /*1*/ fun <get-values>(): kotlin.collections.MutableCollection<V>
     public abstract fun clear(): kotlin.Unit
-    public open fun compute(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V!, out V!>!): V!
-    public open fun computeIfAbsent(/*0*/ p0: K!, /*1*/ p1: java.util.function.Function<in K!, out V!>!): V!
-    public open fun computeIfPresent(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V!, out V!>!): V!
+    public open fun compute(/*0*/ p0: K, /*1*/ p1: java.util.function.BiFunction<in K, in V?, out V?>): V?
+    public open fun computeIfAbsent(/*0*/ p0: K, /*1*/ p1: java.util.function.Function<in K, out V>): V
+    public open fun computeIfPresent(/*0*/ p0: K, /*1*/ p1: java.util.function.BiFunction<in K, in V, out V?>): V?
     public abstract override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: K): kotlin.Boolean
     public abstract override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: V): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in K!, in V!>!): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in K, in V>): kotlin.Unit
     public abstract override /*1*/ /*fake_override*/ fun get(/*0*/ key: K): V?
     @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: K, /*1*/ defaultValue: V): V
     public abstract override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-    public open fun merge(/*0*/ p0: K!, /*1*/ p1: V!, /*2*/ p2: java.util.function.BiFunction<in V!, in V!, out V!>!): V!
+    public open fun merge(/*0*/ p0: K, /*1*/ p1: V, /*2*/ p2: java.util.function.BiFunction<in V, in V, out V?>): V?
     public abstract fun put(/*0*/ key: K, /*1*/ value: V): V?
     public abstract fun putAll(/*0*/ from: kotlin.collections.Map<out K, V>): kotlin.Unit
-    public open fun putIfAbsent(/*0*/ p0: K!, /*1*/ p1: V!): V!
+    public open fun putIfAbsent(/*0*/ p0: K, /*1*/ p1: V): V?
     public abstract fun remove(/*0*/ key: K): V?
     @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open fun remove(/*0*/ key: K, /*1*/ value: V): kotlin.Boolean
-    public open fun replace(/*0*/ p0: K!, /*1*/ p1: V!): V!
-    public open fun replace(/*0*/ p0: K!, /*1*/ p1: V!, /*2*/ p2: V!): kotlin.Boolean
-    public open fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in K!, in V!, out V!>!): kotlin.Unit
+    public open fun replace(/*0*/ p0: K, /*1*/ p1: V): V?
+    public open fun replace(/*0*/ p0: K, /*1*/ p1: V, /*2*/ p2: V): kotlin.Boolean
+    public open fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in K, in V, out V>): kotlin.Unit
 
     public interface MutableEntry</*0*/ K, /*1*/ V> : kotlin.collections.Map.Entry<K, V> {
         public abstract override /*1*/ /*fake_override*/ val key: K
@@ -261,13 +261,13 @@ public interface MutableSet</*0*/ E> : kotlin.collections.Set<E>, kotlin.collect
     public open override /*2*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.Consumer<in E!>!): kotlin.Unit
     public abstract override /*2*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     public abstract override /*2*/ fun iterator(): kotlin.collections.MutableIterator<E>
-    public open override /*2*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<E!>!
+    public open override /*2*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<E>
     public abstract override /*1*/ fun remove(/*0*/ element: E): kotlin.Boolean
     public abstract override /*1*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<E>): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun removeIf(/*0*/ p0: java.util.function.Predicate<in E!>!): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun removeIf(/*0*/ p0: java.util.function.Predicate<in E>): kotlin.Boolean
     public abstract override /*1*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<E>): kotlin.Boolean
-    public open override /*2*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<E!>!
-    public open override /*2*/ /*fake_override*/ fun stream(): java.util.stream.Stream<E!>!
+    public open override /*2*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<E!>
+    public open override /*2*/ /*fake_override*/ fun stream(): java.util.stream.Stream<E>
 }
 
 public interface Set</*0*/ out E> : kotlin.collections.Collection<E> {
@@ -278,9 +278,9 @@ public interface Set</*0*/ out E> : kotlin.collections.Collection<E> {
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.Consumer<in E!>!): kotlin.Unit
     public abstract override /*1*/ fun isEmpty(): kotlin.Boolean
     public abstract override /*1*/ fun iterator(): kotlin.collections.Iterator<E>
-    public open override /*1*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<E!>!
-    public open override /*1*/ fun spliterator(): java.util.Spliterator<@kotlin.UnsafeVariance E!>!
-    public open override /*1*/ /*fake_override*/ fun stream(): java.util.stream.Stream<E!>!
+    public open override /*1*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<E>
+    public open override /*1*/ fun spliterator(): java.util.Spliterator<@kotlin.UnsafeVariance E!>
+    public open override /*1*/ /*fake_override*/ fun stream(): java.util.stream.Stream<E>
 }
 
 public abstract class ShortIterator : kotlin.collections.Iterator<kotlin.Short> {
diff --git a/compiler/testData/builtin-classes/java8/kotlin-ranges.txt b/compiler/testData/builtin-classes/java8/kotlin-ranges.txt
index 8c77e127966..25d001cf812 100644
--- a/compiler/testData/builtin-classes/java8/kotlin-ranges.txt
+++ b/compiler/testData/builtin-classes/java8/kotlin-ranges.txt
@@ -11,7 +11,7 @@ public open class CharProgression : kotlin.collections.Iterable<kotlin.Char> {
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.Consumer<in kotlin.Char!>!): kotlin.Unit
     public open fun isEmpty(): kotlin.Boolean
     public open override /*1*/ fun iterator(): kotlin.collections.CharIterator
-    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.Char!>!
+    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.Char>
 
     public companion object Companion {
         /*primary*/ private constructor Companion()
@@ -53,7 +53,7 @@ public final class CharRange : kotlin.ranges.CharProgression, kotlin.ranges.Clos
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.Consumer<in kotlin.Char!>!): kotlin.Unit
     public open override /*2*/ fun isEmpty(): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.CharIterator
-    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.Char!>!
+    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.Char>
 
     public companion object Companion {
         /*primary*/ private constructor Companion()
@@ -82,7 +82,7 @@ public open class IntProgression : kotlin.collections.Iterable<kotlin.Int> {
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.Consumer<in kotlin.Int!>!): kotlin.Unit
     public open fun isEmpty(): kotlin.Boolean
     public open override /*1*/ fun iterator(): kotlin.collections.IntIterator
-    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.Int!>!
+    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.Int>
 
     public companion object Companion {
         /*primary*/ private constructor Companion()
@@ -124,7 +124,7 @@ public final class IntRange : kotlin.ranges.IntProgression, kotlin.ranges.Closed
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.Consumer<in kotlin.Int!>!): kotlin.Unit
     public open override /*2*/ fun isEmpty(): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.IntIterator
-    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.Int!>!
+    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.Int>
 
     public companion object Companion {
         /*primary*/ private constructor Companion()
@@ -144,7 +144,7 @@ public open class LongProgression : kotlin.collections.Iterable<kotlin.Long> {
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.Consumer<in kotlin.Long!>!): kotlin.Unit
     public open fun isEmpty(): kotlin.Boolean
     public open override /*1*/ fun iterator(): kotlin.collections.LongIterator
-    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.Long!>!
+    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.Long>
 
     public companion object Companion {
         /*primary*/ private constructor Companion()
@@ -186,7 +186,7 @@ public final class LongRange : kotlin.ranges.LongProgression, kotlin.ranges.Clos
     public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.Consumer<in kotlin.Long!>!): kotlin.Unit
     public open override /*2*/ fun isEmpty(): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.LongIterator
-    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.Long!>!
+    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.Long>
 
     public companion object Companion {
         /*primary*/ private constructor Companion()
diff --git a/compiler/testData/diagnostics/testsWithJava8/specialBuiltIns/hashtableInheritance.txt b/compiler/testData/diagnostics/testsWithJava8/specialBuiltIns/hashtableInheritance.txt
index c32f9b0d7a4..5f7affcde97 100644
--- a/compiler/testData/diagnostics/testsWithJava8/specialBuiltIns/hashtableInheritance.txt
+++ b/compiler/testData/diagnostics/testsWithJava8/specialBuiltIns/hashtableInheritance.txt
@@ -17,15 +17,15 @@ public final class C1 : java.util.Hashtable<kotlin.String, kotlin.Int> {
     invisible_fake open override /*1*/ /*fake_override*/ fun addEntry(/*0*/ p0: kotlin.Int, /*1*/ p1: kotlin.String!, /*2*/ p2: kotlin.Int!, /*3*/ p3: kotlin.Int): kotlin.Unit
     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 compute(/*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 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*/ /*fake_override*/ fun compute(/*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 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*/ /*fake_override*/ fun contains(/*0*/ p0: 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 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
+    public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String!, in kotlin.Int!>): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.Int?
     invisible_fake open override /*1*/ /*fake_override*/ fun </*0*/ T : kotlin.Any!> getEnumeration(/*0*/ p0: kotlin.Int): java.util.Enumeration<T!>!
     invisible_fake open override /*1*/ /*fake_override*/ fun </*0*/ T : kotlin.Any!> getIterator(/*0*/ p0: kotlin.Int): kotlin.collections.(Mutable)Iterator<T!>!
@@ -33,18 +33,18 @@ public final class C1 : java.util.Hashtable<kotlin.String, kotlin.Int> {
     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 keys(): java.util.Enumeration<kotlin.String!>!
-    public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int!, in kotlin.Int!, out kotlin.Int!>!): kotlin.Int!
+    public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun put(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun putAll(/*0*/ from: kotlin.collections.Map<out kotlin.String!, kotlin.Int!>): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int!
+    public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int?
     invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ p0: java.io.ObjectInputStream!): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun reconstitutionPut(/*0*/ p0: kotlin.Array<(out) java.util.Hashtable.Entry<*, *>!>!, /*1*/ p1: kotlin.String!, /*2*/ p2: kotlin.Int!): kotlin.Unit
     protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun rehash(): kotlin.Unit
     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!): 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
+    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
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     invisible_fake open override /*1*/ /*fake_override*/ fun writeObject(/*0*/ p0: java.io.ObjectOutputStream!): kotlin.Unit
 }
@@ -66,15 +66,15 @@ public final class C2 : java.util.Hashtable<kotlin.String, kotlin.Int> {
     invisible_fake open override /*1*/ /*fake_override*/ fun addEntry(/*0*/ p0: kotlin.Int, /*1*/ p1: kotlin.String!, /*2*/ p2: kotlin.Int!, /*3*/ p3: kotlin.Int): kotlin.Unit
     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 compute(/*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 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*/ /*fake_override*/ fun compute(/*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 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*/ /*fake_override*/ fun contains(/*0*/ p0: 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 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
+    public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String!, in kotlin.Int!>): kotlin.Unit
     public open override /*1*/ fun get(/*0*/ key: kotlin.String): kotlin.Int
     invisible_fake open override /*1*/ /*fake_override*/ fun </*0*/ T : kotlin.Any!> getEnumeration(/*0*/ p0: kotlin.Int): java.util.Enumeration<T!>!
     invisible_fake open override /*1*/ /*fake_override*/ fun </*0*/ T : kotlin.Any!> getIterator(/*0*/ p0: kotlin.Int): kotlin.collections.(Mutable)Iterator<T!>!
@@ -82,18 +82,18 @@ public final class C2 : java.util.Hashtable<kotlin.String, kotlin.Int> {
     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 keys(): java.util.Enumeration<kotlin.String!>!
-    public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int!, in kotlin.Int!, out kotlin.Int!>!): kotlin.Int!
+    public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun put(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun putAll(/*0*/ from: kotlin.collections.Map<out kotlin.String!, kotlin.Int!>): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int!
+    public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int?
     invisible_fake open override /*1*/ /*fake_override*/ fun readObject(/*0*/ p0: java.io.ObjectInputStream!): kotlin.Unit
     invisible_fake open override /*1*/ /*fake_override*/ fun reconstitutionPut(/*0*/ p0: kotlin.Array<(out) java.util.Hashtable.Entry<*, *>!>!, /*1*/ p1: kotlin.String!, /*2*/ p2: kotlin.Int!): kotlin.Unit
     protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun rehash(): kotlin.Unit
     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!): 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
+    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
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
     invisible_fake open override /*1*/ /*fake_override*/ fun writeObject(/*0*/ p0: java.io.ObjectOutputStream!): kotlin.Unit
 }
diff --git a/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/blackListed.txt b/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/blackListed.txt
index 162fb4d9578..bd546a2c88e 100644
--- a/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/blackListed.txt
+++ b/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/blackListed.txt
@@ -22,17 +22,17 @@ public abstract class A : kotlin.collections.MutableList<kotlin.String> {
     public abstract override /*1*/ /*fake_override*/ fun lastIndexOf(/*0*/ element: kotlin.String): kotlin.Int
     public abstract override /*1*/ /*fake_override*/ fun listIterator(): kotlin.collections.MutableListIterator<kotlin.String>
     public abstract override /*1*/ /*fake_override*/ fun listIterator(/*0*/ index: kotlin.Int): kotlin.collections.MutableListIterator<kotlin.String>
-    public open override /*1*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<kotlin.String!>!
+    public open override /*1*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<kotlin.String>
     public abstract override /*1*/ /*fake_override*/ fun remove(/*0*/ element: kotlin.String): kotlin.Boolean
     public abstract override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
     public abstract override /*1*/ /*fake_override*/ fun removeAt(/*0*/ index: kotlin.Int): kotlin.String
-    public open override /*1*/ /*fake_override*/ fun removeIf(/*0*/ p0: java.util.function.Predicate<in kotlin.String!>!): kotlin.Boolean
-    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 removeIf(/*0*/ p0: java.util.function.Predicate<in kotlin.String>): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.UnaryOperator<kotlin.String>): kotlin.Unit
     public abstract override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
     public abstract override /*1*/ /*fake_override*/ fun set(/*0*/ index: kotlin.Int, /*1*/ element: kotlin.String): kotlin.String
     public open override /*1*/ /*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!>!
-    public open override /*1*/ /*fake_override*/ fun stream(): java.util.stream.Stream<kotlin.String!>!
+    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.String!>
+    public open override /*1*/ /*fake_override*/ fun stream(): java.util.stream.Stream<kotlin.String>
     public abstract 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 toString(): kotlin.String
 }
diff --git a/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/getOrDefault.txt b/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/getOrDefault.txt
index f2bd87254ba..7ca4d364707 100644
--- a/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/getOrDefault.txt
+++ b/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/getOrDefault.txt
@@ -11,7 +11,7 @@ public abstract class A : kotlin.collections.Map<kotlin.Int, kotlin.String> {
     public abstract override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.Int): kotlin.Boolean
     public abstract override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.String): kotlin.Boolean
     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.Int!, in kotlin.String!>!): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.Int, in kotlin.String>): kotlin.Unit
     public abstract override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.Int): kotlin.String?
     @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.Int, /*1*/ defaultValue: kotlin.String): kotlin.String
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
diff --git a/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/mutableMapRemove.txt b/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/mutableMapRemove.txt
index 2c6c232d813..51c970dec72 100644
--- a/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/mutableMapRemove.txt
+++ b/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/mutableMapRemove.txt
@@ -12,26 +12,26 @@ public final class KotlinMap1</*0*/ K, /*1*/ V> : java.util.AbstractMap<K, V> {
     public open override /*1*/ /*fake_override*/ val values: kotlin.collections.MutableCollection<V!>
     public open override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
     protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any!
-    public open override /*1*/ /*fake_override*/ fun compute(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V!, out V!>!): V!
-    public open override /*1*/ /*fake_override*/ fun computeIfAbsent(/*0*/ p0: K!, /*1*/ p1: java.util.function.Function<in K!, out V!>!): V!
-    public open override /*1*/ /*fake_override*/ fun computeIfPresent(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V!, out V!>!): V!
+    public open override /*1*/ /*fake_override*/ fun compute(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V?, out V?>): V?
+    public open override /*1*/ /*fake_override*/ fun computeIfAbsent(/*0*/ p0: K!, /*1*/ p1: java.util.function.Function<in K!, out V!>): V!
+    public open override /*1*/ /*fake_override*/ fun computeIfPresent(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V, out V?>): V?
     public open override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: K!): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: V!): kotlin.Boolean
     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 K!, in V!>!): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in K!, in V!>): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: K!): V?
     @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: K!, /*1*/ defaultValue: V!): V!
     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 merge(/*0*/ p0: K!, /*1*/ p1: V!, /*2*/ p2: java.util.function.BiFunction<in V!, in V!, out V!>!): V!
+    public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: K!, /*1*/ p1: V, /*2*/ p2: java.util.function.BiFunction<in V, in V, out V?>): 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*/ from: kotlin.collections.Map<out K!, V!>): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: K!, /*1*/ p1: V!): V!
+    public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: K!, /*1*/ p1: V!): V?
     public open override /*1*/ fun remove(/*0*/ x: K, /*1*/ y: V): kotlin.Boolean
     public open override /*1*/ /*fake_override*/ fun remove(/*0*/ key: K!): V?
-    public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: K!, /*1*/ p1: V!): V!
+    public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: K!, /*1*/ p1: V!): V?
     public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: K!, /*1*/ p1: V!, /*2*/ p2: V!): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in K!, in V!, out V!>!): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in K!, in V!, out V!>): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
 
@@ -45,25 +45,25 @@ public final class KotlinMap2 : java.util.AbstractMap<kotlin.String, kotlin.Int>
     public open override /*1*/ /*fake_override*/ val values: kotlin.collections.MutableCollection<kotlin.Int!>
     public open override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
     protected/*protected and package*/ open override /*1*/ /*fake_override*/ fun clone(): kotlin.Any!
-    public open override /*1*/ /*fake_override*/ fun compute(/*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 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*/ /*fake_override*/ fun compute(/*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 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*/ /*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 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
+    public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String!, in kotlin.Int!>): kotlin.Unit
     public open override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.Int?
     @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent 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
     public open override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int!, in kotlin.Int!, out kotlin.Int!>!): kotlin.Int!
+    public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun put(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Int?
     public open override /*1*/ /*fake_override*/ fun putAll(/*0*/ from: kotlin.collections.Map<out kotlin.String!, kotlin.Int!>): kotlin.Unit
-    public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int!
+    public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int?
     public open override /*1*/ fun remove(/*0*/ x: kotlin.String, /*1*/ y: 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 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!): 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
+    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
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
diff --git a/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/removeIf.txt b/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/removeIf.txt
index 711a2fdc1f2..cd844d42445 100644
--- a/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/removeIf.txt
+++ b/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/removeIf.txt
@@ -14,12 +14,12 @@ public interface A : kotlin.collections.MutableCollection<kotlin.String> {
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public abstract override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     public abstract override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.MutableIterator<kotlin.String>
-    public open override /*1*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<kotlin.String!>!
+    public open override /*1*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<kotlin.String>
     public abstract override /*1*/ /*fake_override*/ fun remove(/*0*/ element: kotlin.String): kotlin.Boolean
     public abstract override /*1*/ /*fake_override*/ fun removeAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
     public open override /*1*/ fun removeIf(/*0*/ x: java.util.function.Predicate<in kotlin.String>): kotlin.Boolean
     public abstract override /*1*/ /*fake_override*/ fun retainAll(/*0*/ elements: kotlin.collections.Collection<kotlin.String>): kotlin.Boolean
-    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.String!>!
-    public open override /*1*/ /*fake_override*/ fun stream(): java.util.stream.Stream<kotlin.String!>!
+    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.String!>
+    public open override /*1*/ /*fake_override*/ fun stream(): java.util.stream.Stream<kotlin.String>
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
diff --git a/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/stream.txt b/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/stream.txt
index a1fcf29ef04..6e843d7169d 100644
--- a/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/stream.txt
+++ b/compiler/testData/diagnostics/testsWithJava8/targetedBuiltIns/stream.txt
@@ -11,8 +11,8 @@ public interface A : kotlin.collections.Collection<kotlin.String> {
     public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
     public abstract override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
     public abstract override /*1*/ /*fake_override*/ fun iterator(): kotlin.collections.Iterator<kotlin.String>
-    public open override /*1*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<kotlin.String!>!
-    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.String!>!
+    public open override /*1*/ /*fake_override*/ fun parallelStream(): java.util.stream.Stream<kotlin.String>
+    public open override /*1*/ /*fake_override*/ fun spliterator(): java.util.Spliterator<kotlin.String!>
     public open override /*1*/ fun stream(): java.util.stream.Stream<kotlin.String>
     public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
 }
diff --git a/compiler/testData/loadJava8/compiledJava/MapRemove.txt b/compiler/testData/loadJava8/compiledJava/MapRemove.txt
index c768c3fb3a4..6e40bf72fba 100644
--- a/compiler/testData/loadJava8/compiledJava/MapRemove.txt
+++ b/compiler/testData/loadJava8/compiledJava/MapRemove.txt
@@ -10,24 +10,24 @@ public open class MapRemove {
         public abstract override /*1*/ /*fake_override*/ val size: kotlin.Int
         public abstract override /*1*/ /*fake_override*/ val values: kotlin.collections.MutableCollection<V!>
         public abstract override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun compute(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V!, out V!>!): V!
-        public open override /*1*/ /*fake_override*/ fun computeIfAbsent(/*0*/ p0: K!, /*1*/ p1: java.util.function.Function<in K!, out V!>!): V!
-        public open override /*1*/ /*fake_override*/ fun computeIfPresent(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V!, out V!>!): V!
+        public open override /*1*/ /*fake_override*/ fun compute(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V?, out V?>): V?
+        public open override /*1*/ /*fake_override*/ fun computeIfAbsent(/*0*/ p0: K!, /*1*/ p1: java.util.function.Function<in K!, out V!>): V!
+        public open override /*1*/ /*fake_override*/ fun computeIfPresent(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V, out V?>): V?
         public abstract override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: K!): kotlin.Boolean
         public abstract override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: V!): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in K!, in V!>!): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in K!, in V!>): kotlin.Unit
         public abstract override /*1*/ /*fake_override*/ fun get(/*0*/ key: K!): V?
         @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: K!, /*1*/ defaultValue: V!): V!
         public abstract override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: K!, /*1*/ p1: V!, /*2*/ p2: java.util.function.BiFunction<in V!, in V!, out V!>!): V!
+        public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: K!, /*1*/ p1: V, /*2*/ p2: java.util.function.BiFunction<in V, in V, out V?>): V?
         public abstract override /*1*/ /*fake_override*/ fun put(/*0*/ key: K!, /*1*/ value: V!): V?
         public abstract override /*1*/ /*fake_override*/ fun putAll(/*0*/ from: kotlin.collections.Map<out K!, V!>): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: K!, /*1*/ p1: V!): V!
+        public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: K!, /*1*/ p1: V!): V?
         public abstract override /*1*/ /*fake_override*/ fun remove(/*0*/ key: K!): V?
         public open override /*1*/ fun remove(/*0*/ key: K!, /*1*/ value: V!): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: K!, /*1*/ p1: V!): V!
+        public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: K!, /*1*/ p1: V!): V?
         public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: K!, /*1*/ p1: V!, /*2*/ p2: V!): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in K!, in V!, out V!>!): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in K!, in V!, out V!>): kotlin.Unit
     }
 
     public abstract inner class MyMapString : kotlin.collections.MutableMap<kotlin.String!, kotlin.Int!> {
@@ -37,24 +37,24 @@ public open class MapRemove {
         public abstract override /*1*/ /*fake_override*/ val size: kotlin.Int
         public abstract override /*1*/ /*fake_override*/ val values: kotlin.collections.MutableCollection<kotlin.Int!>
         public abstract override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun compute(/*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 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*/ /*fake_override*/ fun compute(/*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 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 abstract override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String!): kotlin.Boolean
         public abstract override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int!): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String!, in kotlin.Int!>!): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String!, in kotlin.Int!>): kotlin.Unit
         public abstract override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.Int?
         @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String!, /*1*/ defaultValue: kotlin.Int!): kotlin.Int!
         public abstract override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int!, in kotlin.Int!, out kotlin.Int!>!): kotlin.Int!
+        public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
         public abstract override /*1*/ /*fake_override*/ fun put(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Int?
         public abstract override /*1*/ /*fake_override*/ fun putAll(/*0*/ from: kotlin.collections.Map<out kotlin.String!, kotlin.Int!>): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int!
+        public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int?
         public abstract override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!): kotlin.Int?
         public open override /*1*/ fun remove(/*0*/ p0: kotlin.String!, /*1*/ p1: 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!): 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
+        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
     }
 
     public abstract inner class MyMapStringInvalid : kotlin.collections.MutableMap<kotlin.String!, kotlin.Int!> {
@@ -64,24 +64,24 @@ public open class MapRemove {
         public abstract override /*1*/ /*fake_override*/ val size: kotlin.Int
         public abstract override /*1*/ /*fake_override*/ val values: kotlin.collections.MutableCollection<kotlin.Int!>
         public abstract override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun compute(/*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 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*/ /*fake_override*/ fun compute(/*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 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 abstract override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String!): kotlin.Boolean
         public abstract override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int!): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String!, in kotlin.Int!>!): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String!, in kotlin.Int!>): kotlin.Unit
         public abstract override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.Int?
         @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String!, /*1*/ defaultValue: kotlin.Int!): kotlin.Int!
         public abstract override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int!, in kotlin.Int!, out kotlin.Int!>!): kotlin.Int!
+        public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
         public abstract override /*1*/ /*fake_override*/ fun put(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Int?
         public abstract override /*1*/ /*fake_override*/ fun putAll(/*0*/ from: kotlin.collections.Map<out kotlin.String!, kotlin.Int!>): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int!
+        public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int?
         public abstract override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!): kotlin.Int?
         public open fun remove(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Boolean
         @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open override /*1*/ /*fake_override*/ /*isHiddenToOvercomeSignatureClash*/ 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!): 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
+        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
     }
 }
diff --git a/compiler/testData/loadJava8/sourceJava/MapRemove.txt b/compiler/testData/loadJava8/sourceJava/MapRemove.txt
index 20f3102e354..cdf26cd7418 100644
--- a/compiler/testData/loadJava8/sourceJava/MapRemove.txt
+++ b/compiler/testData/loadJava8/sourceJava/MapRemove.txt
@@ -10,24 +10,24 @@ public open class MapRemove {
         public abstract override /*1*/ /*fake_override*/ val size: kotlin.Int
         public abstract override /*1*/ /*fake_override*/ val values: kotlin.collections.MutableCollection<V!>
         public abstract override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun compute(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V!, out V!>!): V!
-        public open override /*1*/ /*fake_override*/ fun computeIfAbsent(/*0*/ p0: K!, /*1*/ p1: java.util.function.Function<in K!, out V!>!): V!
-        public open override /*1*/ /*fake_override*/ fun computeIfPresent(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V!, out V!>!): V!
+        public open override /*1*/ /*fake_override*/ fun compute(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V?, out V?>): V?
+        public open override /*1*/ /*fake_override*/ fun computeIfAbsent(/*0*/ p0: K!, /*1*/ p1: java.util.function.Function<in K!, out V!>): V!
+        public open override /*1*/ /*fake_override*/ fun computeIfPresent(/*0*/ p0: K!, /*1*/ p1: java.util.function.BiFunction<in K!, in V, out V?>): V?
         public abstract override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: K!): kotlin.Boolean
         public abstract override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: V!): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in K!, in V!>!): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in K!, in V!>): kotlin.Unit
         public abstract override /*1*/ /*fake_override*/ fun get(/*0*/ key: K!): V?
         @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: K!, /*1*/ defaultValue: V!): V!
         public abstract override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: K!, /*1*/ p1: V!, /*2*/ p2: java.util.function.BiFunction<in V!, in V!, out V!>!): V!
+        public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: K!, /*1*/ p1: V, /*2*/ p2: java.util.function.BiFunction<in V, in V, out V?>): V?
         public abstract override /*1*/ /*fake_override*/ fun put(/*0*/ key: K!, /*1*/ value: V!): V?
         public abstract override /*1*/ /*fake_override*/ fun putAll(/*0*/ from: kotlin.collections.Map<out K!, V!>): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: K!, /*1*/ p1: V!): V!
+        public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: K!, /*1*/ p1: V!): V?
         public abstract override /*1*/ /*fake_override*/ fun remove(/*0*/ key: K!): V?
         public open override /*1*/ fun remove(/*0*/ key: K!, /*1*/ value: V!): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: K!, /*1*/ p1: V!): V!
+        public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: K!, /*1*/ p1: V!): V?
         public open override /*1*/ /*fake_override*/ fun replace(/*0*/ p0: K!, /*1*/ p1: V!, /*2*/ p2: V!): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in K!, in V!, out V!>!): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun replaceAll(/*0*/ p0: java.util.function.BiFunction<in K!, in V!, out V!>): kotlin.Unit
     }
 
     public abstract inner class MyMapString : kotlin.collections.MutableMap<kotlin.String!, kotlin.Int!> {
@@ -37,24 +37,24 @@ public open class MapRemove {
         public abstract override /*1*/ /*fake_override*/ val size: kotlin.Int
         public abstract override /*1*/ /*fake_override*/ val values: kotlin.collections.MutableCollection<kotlin.Int!>
         public abstract override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun compute(/*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 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*/ /*fake_override*/ fun compute(/*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 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 abstract override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String!): kotlin.Boolean
         public abstract override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int!): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String!, in kotlin.Int!>!): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String!, in kotlin.Int!>): kotlin.Unit
         public abstract override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.Int?
         @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String!, /*1*/ defaultValue: kotlin.Int!): kotlin.Int!
         public abstract override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int!, in kotlin.Int!, out kotlin.Int!>!): kotlin.Int!
+        public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
         public abstract override /*1*/ /*fake_override*/ fun put(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Int?
         public abstract override /*1*/ /*fake_override*/ fun putAll(/*0*/ from: kotlin.collections.Map<out kotlin.String!, kotlin.Int!>): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int!
+        public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int?
         public abstract override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!): kotlin.Int?
         public open override /*1*/ fun remove(/*0*/ x: kotlin.String!, /*1*/ y: 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!): 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
+        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
     }
 
     public abstract inner class MyMapStringInvalid : kotlin.collections.MutableMap<kotlin.String!, kotlin.Int!> {
@@ -64,24 +64,24 @@ public open class MapRemove {
         public abstract override /*1*/ /*fake_override*/ val size: kotlin.Int
         public abstract override /*1*/ /*fake_override*/ val values: kotlin.collections.MutableCollection<kotlin.Int!>
         public abstract override /*1*/ /*fake_override*/ fun clear(): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun compute(/*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 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*/ /*fake_override*/ fun compute(/*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 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 abstract override /*1*/ /*fake_override*/ fun containsKey(/*0*/ key: kotlin.String!): kotlin.Boolean
         public abstract override /*1*/ /*fake_override*/ fun containsValue(/*0*/ value: kotlin.Int!): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String!, in kotlin.Int!>!): kotlin.Unit
+        public open override /*1*/ /*fake_override*/ fun forEach(/*0*/ p0: java.util.function.BiConsumer<in kotlin.String!, in kotlin.Int!>): kotlin.Unit
         public abstract override /*1*/ /*fake_override*/ fun get(/*0*/ key: kotlin.String!): kotlin.Int?
         @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open override /*1*/ /*fake_override*/ fun getOrDefault(/*0*/ key: kotlin.String!, /*1*/ defaultValue: kotlin.Int!): kotlin.Int!
         public abstract override /*1*/ /*fake_override*/ fun isEmpty(): kotlin.Boolean
-        public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int!, in kotlin.Int!, out kotlin.Int!>!): kotlin.Int!
+        public open override /*1*/ /*fake_override*/ fun merge(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int, /*2*/ p2: java.util.function.BiFunction<in kotlin.Int, in kotlin.Int, out kotlin.Int?>): kotlin.Int?
         public abstract override /*1*/ /*fake_override*/ fun put(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Int?
         public abstract override /*1*/ /*fake_override*/ fun putAll(/*0*/ from: kotlin.collections.Map<out kotlin.String!, kotlin.Int!>): kotlin.Unit
-        public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int!
+        public open override /*1*/ /*fake_override*/ fun putIfAbsent(/*0*/ p0: kotlin.String!, /*1*/ p1: kotlin.Int!): kotlin.Int?
         public abstract override /*1*/ /*fake_override*/ fun remove(/*0*/ key: kotlin.String!): kotlin.Int?
         public open fun remove(/*0*/ key: kotlin.String!, /*1*/ value: kotlin.Int!): kotlin.Boolean
         @kotlin.SinceKotlin(version = "1.1") @kotlin.internal.PlatformDependent public open override /*1*/ /*fake_override*/ /*isHiddenToOvercomeSignatureClash*/ 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!): 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
+        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
     }
 }
diff --git a/idea/idea-completion/testData/basic/java8/CollectionMethods.kt b/idea/idea-completion/testData/basic/java8/CollectionMethods.kt
index 99474ad5c37..fbf8832e183 100644
--- a/idea/idea-completion/testData/basic/java8/CollectionMethods.kt
+++ b/idea/idea-completion/testData/basic/java8/CollectionMethods.kt
@@ -2,6 +2,6 @@ fun foo(x: MutableList<String>) {
     x.<caret>
 }
 
-// EXIST: {"lookupString":"stream","tailText":"()","typeText":"Stream<String!>!"}
-// EXIST: {"lookupString":"removeIf","tailText":"(Predicate<in String!>!)","typeText":"Boolean"}
-// EXIST: {"lookupString":"removeIf","tailText":" {...} (((String!) -> Boolean)!)","typeText":"Boolean"}
+// EXIST: {"lookupString":"stream","tailText":"()","typeText":"Stream<String>"}
+// EXIST: {"lookupString":"removeIf","tailText":"(Predicate<in String>)","typeText":"Boolean"}
+// EXIST: {"lookupString":"removeIf","tailText":" {...} ((String) -> Boolean)","typeText":"Boolean"}