Document the requirement for 'minus(elements)' to have stable hashCode

#KT-24536

libraries/stdlib/common/src/generated/_Collections.kt

@@ -1921,6 +1921,9 @@ public operator fun <T> Iterable<T>.minus(element: T): List<T> {
 
 /**
  * Returns a list containing all elements of the original collection except the elements contained in the given [elements] array.
+ * 
+ * The [elements] array may be converted to a [HashSet] to speed up the operation, thus the elements are required to have
+ * a correct and stable implementation of `hashCode()` that doesn't change between successive invocations.
  */
 public operator fun <T> Iterable<T>.minus(elements: Array<out T>): List<T> {
     if (elements.isEmpty()) return this.toList()
@@ -1930,6 +1933,9 @@ public operator fun <T> Iterable<T>.minus(elements: Array<out T>): List<T> {
 
 /**
  * Returns a list containing all elements of the original collection except the elements contained in the given [elements] collection.
+ * 
+ * The [elements] collection may be converted to a [HashSet] to speed up the operation, thus the elements are required to have
+ * a correct and stable implementation of `hashCode()` that doesn't change between successive invocations.
  */
 public operator fun <T> Iterable<T>.minus(elements: Iterable<T>): List<T> {
     val other = elements.convertToSetForSetOperationWith(this)
@@ -1940,6 +1946,9 @@ public operator fun <T> Iterable<T>.minus(elements: Iterable<T>): List<T> {
 
 /**
  * Returns a list containing all elements of the original collection except the elements contained in the given [elements] sequence.
+ * 
+ * The [elements] sequence may be converted to a [HashSet] to speed up the operation, thus the elements are required to have
+ * a correct and stable implementation of `hashCode()` that doesn't change between successive invocations.
  */
 public operator fun <T> Iterable<T>.minus(elements: Sequence<T>): List<T> {
     val other = elements.toHashSet()