src/share/classes/java/util/Collections.java

rev 7682 : 8021591: Additional explicit null checks
Reviewed-by: duke

*** 3870,3879 ****
--- 3870,3880 ----
              }
              public boolean retainAll(Collection<?> c) {
                  return batchRemove(c, true);
              }
              private boolean batchRemove(Collection<?> c, boolean complement) {
+                 Objects.requireNonNull(c);
                  boolean modified = false;
                  Iterator<Map.Entry<K,V>> it = iterator();
                  while (it.hasNext()) {
                      if (c.contains(it.next()) != complement) {
                          it.remove();