Fix doc wording around covariance/invariance

libraries/stdlib/jvm/src/kotlin/collections/AbstractMutableCollection.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -10,7 +10,7 @@ import java.util.AbstractCollection
 /**
  * Provides a skeletal implementation of the [MutableCollection] interface.
  *
- * @param E the type of elements contained in the collection. The collection is invariant on its element type.
+ * @param E the type of elements contained in the collection. The collection is invariant in its element type.
  */
 @SinceKotlin("1.1")
 public actual abstract class AbstractMutableCollection<E> protected actual constructor() : MutableCollection<E>, AbstractCollection<E>() {

libraries/stdlib/jvm/src/kotlin/collections/AbstractMutableList.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -10,7 +10,7 @@ import java.util.AbstractList
 /**
  * Provides a skeletal implementation of the [MutableList] interface.
  *
- * @param E the type of elements contained in the list. The list is invariant on its element type.
+ * @param E the type of elements contained in the list. The list is invariant in its element type.
  */
 @SinceKotlin("1.1")
 public actual abstract class AbstractMutableList<E> protected actual constructor() : MutableList<E>, AbstractList<E>() {

libraries/stdlib/jvm/src/kotlin/collections/AbstractMutableMap.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -12,8 +12,8 @@ import java.util.AbstractMap
  *
  * The implementor is required to implement [entries] property, which should return mutable set of map entries, and [put] function.
  *
- * @param K the type of map keys. The map is invariant on its key type.
- * @param V the type of map values. The map is invariant on its value type.
+ * @param K the type of map keys. The map is invariant in its key type.
+ * @param V the type of map values. The map is invariant in its value type.
  */
 @SinceKotlin("1.1")
 public actual abstract class AbstractMutableMap<K, V> protected actual constructor() : MutableMap<K, V>, AbstractMap<K, V>() {

libraries/stdlib/jvm/src/kotlin/collections/AbstractMutableSet.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -10,7 +10,7 @@ import java.util.AbstractSet
 /**
  * Provides a skeletal implementation of the [MutableSet] interface.
  *
- * @param E the type of elements contained in the set. The set is invariant on its element type.
+ * @param E the type of elements contained in the set. The set is invariant in its element type.
  */
 @SinceKotlin("1.1")
 public actual abstract class AbstractMutableSet<E> protected actual constructor() : MutableSet<E>, AbstractSet<E>() {