diff --git a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java
index d63e745a3ef..fb4978f0d05 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java
@@ -93,7 +93,6 @@ public interface Errors {
     DiagnosticFactory0<JetTypeProjection> PROJECTION_ON_NON_CLASS_TYPE_ARGUMENT = DiagnosticFactory0.create(ERROR, VARIANCE_IN_PROJECTION);
     DiagnosticFactory2<JetTypeReference, JetType, JetType> UPPER_BOUND_VIOLATED = DiagnosticFactory2.create(ERROR);
     DiagnosticFactory0<JetNullableType> REDUNDANT_NULLABLE = DiagnosticFactory0.create(WARNING, NULLABLE_TYPE);
-    DiagnosticFactory1<JetNullableType, JetType> BASE_WITH_NULLABLE_UPPER_BOUND = DiagnosticFactory1.create(WARNING, NULLABLE_TYPE);
     DiagnosticFactory1<JetElement, Integer> WRONG_NUMBER_OF_TYPE_ARGUMENTS = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory2<JetTypeReference, Integer, String> NO_TYPE_ARGUMENTS_ON_RHS = DiagnosticFactory2.create(ERROR);
     DiagnosticFactory1<JetTypeProjection, ClassifierDescriptor> CONFLICTING_PROJECTION = DiagnosticFactory1.create(ERROR, VARIANCE_IN_PROJECTION);
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java
index e51115b54e7..b6964336556 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java
@@ -473,9 +473,6 @@ public class DefaultErrorMessages {
         MAP.put(NULLABLE_SUPERTYPE, "A supertype cannot be nullable");
         MAP.put(DYNAMIC_SUPERTYPE, "A supertype cannot be dynamic");
         MAP.put(REDUNDANT_NULLABLE, "Redundant '?'");
-        MAP.put(BASE_WITH_NULLABLE_UPPER_BOUND, "''{0}'' has a nullable upper bound. " +
-                                                "This means that a value of this type may be null. " +
-                                                "Using ''{0}?'' is likely to mislead the reader", RENDER_TYPE);
         MAP.put(UNSAFE_CALL, "Only safe (?.) or non-null asserted (!!.) calls are allowed on a nullable receiver of type {0}", RENDER_TYPE);
         MAP.put(AMBIGUOUS_LABEL, "Ambiguous label");
         MAP.put(UNSUPPORTED, "Unsupported [{0}]", STRING);
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/resolve/TypeResolver.kt b/compiler/frontend/src/org/jetbrains/kotlin/resolve/TypeResolver.kt
index 41abc8f32d8..6509a4f782c 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/resolve/TypeResolver.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/resolve/TypeResolver.kt
@@ -231,9 +231,6 @@ public class TypeResolver(
                 if (baseType.isNullable() || innerType is JetNullableType || innerType is JetDynamicType) {
                     c.trace.report(REDUNDANT_NULLABLE.on(nullableType))
                 }
-                else if (c.checkBounds && !baseType.isBare() && TypeUtils.hasNullableSuperType(baseType.getActualType())) {
-                    c.trace.report(BASE_WITH_NULLABLE_UPPER_BOUND.on(nullableType, baseType.getActualType()))
-                }
                 result = baseType.makeNullable()
             }
 
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/nullToGeneric.kt b/compiler/testData/diagnostics/tests/generics/nullability/nullToGeneric.kt
index 5db508c62d6..c831d9dc3f4 100644
--- a/compiler/testData/diagnostics/tests/generics/nullability/nullToGeneric.kt
+++ b/compiler/testData/diagnostics/tests/generics/nullability/nullToGeneric.kt
@@ -1,4 +1,4 @@
-// !DIAGNOSTICS: -UNUSED_PARAMETER,-UNUSED_VARIABLE,-BASE_WITH_NULLABLE_UPPER_BOUND
+// !DIAGNOSTICS: -UNUSED_PARAMETER,-UNUSED_VARIABLE
 
 fun <E> bar(x: E) {}
 
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolation.kt b/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolation.kt
index 66570e97cd7..9ca0087d34c 100644
--- a/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolation.kt
+++ b/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolation.kt
@@ -1,5 +1,5 @@
 // !CHECK_TYPE
-// !DIAGNOSTICS: -UNUSED_PARAMETER, -BASE_WITH_NULLABLE_UPPER_BOUND, -UNUSED_VARIABLE
+// !DIAGNOSTICS: -UNUSED_PARAMETER,-UNUSED_VARIABLE
 
 class A<F> {
     fun <E : F> foo1(x: E) = x
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolationVariance.kt b/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolationVariance.kt
index 6e50f104289..e7f9482058d 100644
--- a/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolationVariance.kt
+++ b/compiler/testData/diagnostics/tests/generics/nullability/tpBoundsViolationVariance.kt
@@ -1,5 +1,5 @@
 // !CHECK_TYPE
-// !DIAGNOSTICS: -UNUSED_PARAMETER, -BASE_WITH_NULLABLE_UPPER_BOUND, -UNUSED_VARIABLE
+// !DIAGNOSTICS: -UNUSED_PARAMETER,-UNUSED_VARIABLE
 
 class A<F> {
     class Inv<Q>
diff --git a/compiler/testData/diagnostics/tests/generics/nullability/tpInBounds.kt b/compiler/testData/diagnostics/tests/generics/nullability/tpInBounds.kt
index c5c0103a568..e393b7b4322 100644
--- a/compiler/testData/diagnostics/tests/generics/nullability/tpInBounds.kt
+++ b/compiler/testData/diagnostics/tests/generics/nullability/tpInBounds.kt
@@ -1,4 +1,4 @@
-// !DIAGNOSTICS: -UNUSED_VALUE,-UNUSED_VARIABLE,-ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE,-BASE_WITH_NULLABLE_UPPER_BOUND,-VARIABLE_WITH_REDUNDANT_INITIALIZER
+// !DIAGNOSTICS: -UNUSED_VALUE,-UNUSED_VARIABLE,-ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE,-VARIABLE_WITH_REDUNDANT_INITIALIZER
 
 class A<T : CharSequence?, E1 : T, E2: T?> {
     fun T.bar() {}
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/equalityConstraintOnNullableType.kt b/compiler/testData/diagnostics/tests/inference/constraints/equalityConstraintOnNullableType.kt
index aae592088d5..152242d6392 100644
--- a/compiler/testData/diagnostics/tests/inference/constraints/equalityConstraintOnNullableType.kt
+++ b/compiler/testData/diagnostics/tests/inference/constraints/equalityConstraintOnNullableType.kt
@@ -1,4 +1,3 @@
-// !DIAGNOSTICS: -BASE_WITH_NULLABLE_UPPER_BOUND
 // !CHECK_TYPE
 interface A<T>
 
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/subtypeConstraintOnNullableType.kt b/compiler/testData/diagnostics/tests/inference/constraints/subtypeConstraintOnNullableType.kt
index c9466330f55..59d59410736 100644
--- a/compiler/testData/diagnostics/tests/inference/constraints/subtypeConstraintOnNullableType.kt
+++ b/compiler/testData/diagnostics/tests/inference/constraints/subtypeConstraintOnNullableType.kt
@@ -1,4 +1,3 @@
-// !DIAGNOSTICS: -BASE_WITH_NULLABLE_UPPER_BOUND
 // !CHECK_TYPE
 interface A<T>
 
diff --git a/compiler/testData/diagnostics/tests/inference/constraints/supertypeConstraintOnNullableType.kt b/compiler/testData/diagnostics/tests/inference/constraints/supertypeConstraintOnNullableType.kt
index 7eb272e4d00..c6689046e89 100644
--- a/compiler/testData/diagnostics/tests/inference/constraints/supertypeConstraintOnNullableType.kt
+++ b/compiler/testData/diagnostics/tests/inference/constraints/supertypeConstraintOnNullableType.kt
@@ -1,4 +1,3 @@
-// !DIAGNOSTICS: -BASE_WITH_NULLABLE_UPPER_BOUND
 // !CHECK_TYPE
 interface A<T>
 
diff --git a/compiler/testData/diagnostics/tests/inference/kt3184.kt b/compiler/testData/diagnostics/tests/inference/kt3184.kt
index 069676a9a52..f92985197d6 100644
--- a/compiler/testData/diagnostics/tests/inference/kt3184.kt
+++ b/compiler/testData/diagnostics/tests/inference/kt3184.kt
@@ -21,6 +21,6 @@ fun tests() {
 }
 
 // from standard library
-operator fun <K, V> MutableMap<K, V>.set(key : K, value : V) : V<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!> = this.put(key, value)
+operator fun <K, V> MutableMap<K, V>.set(key : K, value : V) : V? = this.put(key, value)
 
 fun println(message : Any?) = System.out.println(message)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedCallsForArraySetExpression.kt b/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedCallsForArraySetExpression.kt
index 5f7c70b2979..583ec9f7104 100644
--- a/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedCallsForArraySetExpression.kt
+++ b/compiler/testData/diagnostics/tests/inference/nestedCalls/completeNestedCallsForArraySetExpression.kt
@@ -5,4 +5,4 @@ fun test(map: MutableMap<Int, Int>, t: Int) {
 }
 
 //from library
-operator fun <K, V> MutableMap<K, V>.set(key : K, value : V) : V<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!> = this.put(key, value)
\ No newline at end of file
+operator fun <K, V> MutableMap<K, V>.set(key : K, value : V) : V? = this.put(key, value)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/nullableUpperBound.kt b/compiler/testData/diagnostics/tests/inference/nullableUpperBound.kt
index 358df6853b4..62b9383a669 100644
--- a/compiler/testData/diagnostics/tests/inference/nullableUpperBound.kt
+++ b/compiler/testData/diagnostics/tests/inference/nullableUpperBound.kt
@@ -4,6 +4,6 @@ fun foo(): String? {
     return accept(JV<String?, Unit?>())
 }
 
-fun <R, D> accept(<!UNUSED_PARAMETER!>v<!>: JV<R, D>): R<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!> = null
+fun <R, D> accept(<!UNUSED_PARAMETER!>v<!>: JV<R, D>): R? = null
 
 open class JV<R, D>()
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt3559.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt3559.kt
index 4cd430d0752..4f7b83901c7 100644
--- a/compiler/testData/diagnostics/tests/inference/regressions/kt3559.kt
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt3559.kt
@@ -1,6 +1,6 @@
 // KT-3559 Strange inference failure error message
 
-public inline fun <T:Any, R> let(subj: T?, body: (T) -> R): R<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!> {
+public inline fun <T:Any, R> let(subj: T?, body: (T) -> R): R? {
     return if (subj != null) body(<!DEBUG_INFO_SMARTCAST!>subj<!>) else null
 }
 
diff --git a/compiler/testData/diagnostics/tests/inference/regressions/kt702.kt b/compiler/testData/diagnostics/tests/inference/regressions/kt702.kt
index c5ce05c1686..656f9bba3ad 100644
--- a/compiler/testData/diagnostics/tests/inference/regressions/kt702.kt
+++ b/compiler/testData/diagnostics/tests/inference/regressions/kt702.kt
@@ -6,7 +6,7 @@ fun <T> getJavaClass() : java.lang.Class<T> { <!NO_RETURN_IN_FUNCTION_WITH_BLOCK
 
 public class Throwables() {
     companion object {
-        public fun <X : Throwable?> propagateIfInstanceOf(throwable : Throwable?, declaredType : Class<X<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!>>?) : Unit {
+        public fun <X : Throwable?> propagateIfInstanceOf(throwable : Throwable?, declaredType : Class<X?>?) : Unit {
             if (((throwable != null) && declaredType?.isInstance(throwable)!!))
             {
                 throw declaredType?.cast(throwable)!!
@@ -17,5 +17,4 @@ public class Throwables() {
             propagateIfInstanceOf(throwable, getJavaClass<RuntimeException?>()) // Type inference failed: Mismatch while expanding constraints
         }
     }
-}
-
+}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/kt53.kt b/compiler/testData/diagnostics/tests/kt53.kt
index 6b31ad04a19..be726999125 100644
--- a/compiler/testData/diagnostics/tests/kt53.kt
+++ b/compiler/testData/diagnostics/tests/kt53.kt
@@ -1,4 +1,4 @@
-val <T> T.foo : T<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!>
+val <T> T.foo : T?
     get() = null
 
 fun test(): Int? {
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsBoundMismatch.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsBoundMismatch.kt
index c5517ab355e..579a71baea5 100644
--- a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsBoundMismatch.kt
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsBoundMismatch.kt
@@ -1,4 +1,4 @@
-// !DIAGNOSTICS: -BASE_WITH_NULLABLE_UPPER_BOUND -UNNECESSARY_SAFE_CALL
+// !DIAGNOSTICS: -UNNECESSARY_SAFE_CALL
 
 // MODULE: m1
 // FILE: a.kt
diff --git a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsIndexMismatch.kt b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsIndexMismatch.kt
index e07841631d6..af66c73c557 100644
--- a/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsIndexMismatch.kt
+++ b/compiler/testData/diagnostics/tests/multimodule/duplicateMethod/classGenericsInParamsIndexMismatch.kt
@@ -1,5 +1,3 @@
-// !DIAGNOSTICS: -BASE_WITH_NULLABLE_UPPER_BOUND
-
 // MODULE: m1
 // FILE: a.kt
 package p
diff --git a/compiler/testData/diagnostics/tests/nullableTypes/baseWithNullableUpperBound.kt b/compiler/testData/diagnostics/tests/nullableTypes/baseWithNullableUpperBound.kt
index 4fb7a6bcd0d..c44a90d9212 100644
--- a/compiler/testData/diagnostics/tests/nullableTypes/baseWithNullableUpperBound.kt
+++ b/compiler/testData/diagnostics/tests/nullableTypes/baseWithNullableUpperBound.kt
@@ -9,16 +9,16 @@ fun <NN: Any, TWO_BOUNDS> twoBounds(
 ) where TWO_BOUNDS: Any, TWO_BOUNDS : NN {}
 
 fun <T, N: T, INDIRECT: N> misleadingNullableSimple(
-        <!UNUSED_PARAMETER!>t<!>: T<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!>,
-        <!UNUSED_PARAMETER!>t2<!>: T<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!>,
-        <!UNUSED_PARAMETER!>n<!>: N<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!>,
-        <!UNUSED_PARAMETER!>ind<!>: INDIRECT<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!>
+        <!UNUSED_PARAMETER!>t<!>: T?,
+        <!UNUSED_PARAMETER!>t2<!>: T?,
+        <!UNUSED_PARAMETER!>n<!>: N?,
+        <!UNUSED_PARAMETER!>ind<!>: INDIRECT?
 ) {}
 
 fun <FIRST_BOUND, SECOND_BOUND> misleadingNullableMultiBound(
-        <!UNUSED_PARAMETER!>fb<!>: FIRST_BOUND<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!>,
-        <!UNUSED_PARAMETER!>sb<!>: SECOND_BOUND<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!>
+        <!UNUSED_PARAMETER!>fb<!>: FIRST_BOUND?,
+        <!UNUSED_PARAMETER!>sb<!>: SECOND_BOUND?
 ) where FIRST_BOUND: Any?, FIRST_BOUND: Any, SECOND_BOUND: Any, SECOND_BOUND: Any? {
 }
 
-fun <T> interactionWithRedundant(<!UNUSED_PARAMETER!>t<!>: T<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!><!REDUNDANT_NULLABLE!>?<!>) {}
\ No newline at end of file
+fun <T> interactionWithRedundant(<!UNUSED_PARAMETER!>t<!>: T?<!REDUNDANT_NULLABLE!>?<!>) {}
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/platformTypes/supertypeArgumentsExplicit.kt b/compiler/testData/diagnostics/tests/platformTypes/supertypeArgumentsExplicit.kt
index 51d087d07ff..4b897e4a36a 100644
--- a/compiler/testData/diagnostics/tests/platformTypes/supertypeArgumentsExplicit.kt
+++ b/compiler/testData/diagnostics/tests/platformTypes/supertypeArgumentsExplicit.kt
@@ -1,5 +1,4 @@
 // !EXPLICIT_FLEXIBLE_TYPES
-// !DIAGNOSTICS: -BASE_WITH_NULLABLE_UPPER_BOUND
 
 interface A<T>
 interface B<T>: A<ft<T, T?>>
diff --git a/compiler/testData/diagnostics/tests/regressions/kt312.kt b/compiler/testData/diagnostics/tests/regressions/kt312.kt
index c87bf39327a..347b91a678f 100644
--- a/compiler/testData/diagnostics/tests/regressions/kt312.kt
+++ b/compiler/testData/diagnostics/tests/regressions/kt312.kt
@@ -3,11 +3,10 @@ public inline fun <reified T> Array(n: Int, block: (Int) -> T): Array<T> = null!
 
 // KT-312 Nullability problem when a nullable version of a generic type is returned
 
-fun <T> Array<out T>.safeGet(index : Int) : T<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!> {
+fun <T> Array<out T>.safeGet(index : Int) : T? {
     return if (index < size()) this[index] else null
 }
 
 val args : Array<String> = Array<String>(1, {""})
 val name : String = <!TYPE_MISMATCH!>args.safeGet<String>(0)<!> // No error, must be type mismatch
-val name1 : String? = args.safeGet(0)
-
+val name1 : String? = args.safeGet(0)
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/regressions/kt701.kt b/compiler/testData/diagnostics/tests/regressions/kt701.kt
index 2f262b11241..019099348bb 100644
--- a/compiler/testData/diagnostics/tests/regressions/kt701.kt
+++ b/compiler/testData/diagnostics/tests/regressions/kt701.kt
@@ -3,7 +3,7 @@ fun <T> getJavaClass() : java.lang.Class<T> { return "" <!CAST_NEVER_SUCCEEDS!>a
 
 public class Throwables() {
     companion object {
-        public fun <X : Throwable?> propagateIfInstanceOf(throwable : Throwable?, declaredType : Class<X<!BASE_WITH_NULLABLE_UPPER_BOUND!>?<!>>?) {
+        public fun <X : Throwable?> propagateIfInstanceOf(throwable : Throwable?, declaredType : Class<X?>?) {
             if (((throwable != null) && declaredType?.isInstance(throwable)!!))
             {
                 throw declaredType?.cast(throwable)!!
@@ -14,4 +14,4 @@ public class Throwables() {
             propagateIfInstanceOf(throwable, getJavaClass<RuntimeException?>()) // Type inference failed: Mismatch while expanding constraints
         }
     }
-}
+}
\ No newline at end of file
diff --git a/js/js.libraries/src/core/core.kt b/js/js.libraries/src/core/core.kt
index df8d2999cb2..ed97c02a1ca 100644
--- a/js/js.libraries/src/core/core.kt
+++ b/js/js.libraries/src/core/core.kt
@@ -15,9 +15,6 @@ public fun typeof(a: Any?): String = noImpl
 @native
 public val undefined: Nothing? = noImpl
 
-// Drop this after KT-2093 will be fixed and restore MutableMap.set in Maps.kt from MapsJVM.kt
-/** Provides [] access to maps */
-@Suppress("BASE_WITH_NULLABLE_UPPER_BOUND")
 @native public fun <K, V> MutableMap<K, V>.set(key: K, value: V): V? = noImpl
 
 @library
diff --git a/js/js.libraries/src/core/javautil.kt b/js/js.libraries/src/core/javautil.kt
index 3e50436490f..3bd4ae1838b 100644
--- a/js/js.libraries/src/core/javautil.kt
+++ b/js/js.libraries/src/core/javautil.kt
@@ -70,9 +70,7 @@ public open class LinkedList<E>() : AbstractList<E>() {
     override fun set(index: Int, element: E): E = noImpl
     override fun add(index: Int, element: E): Unit = noImpl
 
-    @Suppress("BASE_WITH_NULLABLE_UPPER_BOUND")
     public fun poll(): E? = noImpl
-    @Suppress("BASE_WITH_NULLABLE_UPPER_BOUND")
     public fun peek(): E? = noImpl
     public fun offer(e: E): Boolean = noImpl
 }
@@ -104,13 +102,10 @@ public open class LinkedHashSet<E>(
 public open class HashMap<K, V>(initialCapacity: Int = DEFAULT_INITIAL_CAPACITY, loadFactor: Float = DEFAULT_LOAD_FACTOR) : MutableMap<K, V> {
     override val size: Int get() = noImpl
     override fun isEmpty(): Boolean = noImpl
-    @Suppress("BASE_WITH_NULLABLE_UPPER_BOUND")
     override fun get(key: K): V? = noImpl
     override fun containsKey(key: K): Boolean = noImpl
-    @Suppress("BASE_WITH_NULLABLE_UPPER_BOUND")
     override fun put(key: K, value: V): V? = noImpl
     override fun putAll(m: Map<out K, V>): Unit = noImpl
-    @Suppress("BASE_WITH_NULLABLE_UPPER_BOUND")
     override fun remove(key: K): V? = noImpl
     override fun clear(): Unit = noImpl
     override fun containsValue(value: V): Boolean = noImpl