8177653: clarify restrictions on Iterator.forEachRemaining

Reviewed-by: martin

jdk/src/java.base/share/classes/java/util/Iterator.java

@@ -109,7 +109,8 @@ public interface Iterator<E> {
      * Exceptions thrown by the action are relayed to the caller.
      * <p>
      * The behavior of an iterator is unspecified if the action modifies the
-     * collection in any way (even by calling the {@link #remove remove} method),
+     * collection in any way (even by calling the {@link #remove remove} method
+     * or other mutator methods of {@code Iterator} subtypes),
      * unless an overriding class has specified a concurrent modification policy.
      * <p>
      * Subsequent behavior of an iterator is unspecified if the action throws an