open fun retainAll(elements: Collection<E>): Boolean
Retains only the elements in this collection that are contained in the specified collection.
Return true if any element was removed from the collection, false if the collection was not modified.
© 2010–2020 JetBrains s.r.o. and Kotlin Programming Language contributors
Licensed under the Apache License, Version 2.0.
https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.collections/-abstract-mutable-list/retain-all.html