public <T extends @Nullable Object> T[] toArray(T[] array) {
      return standardToArray(array);
    }

    @Override
    public boolean contains(@Nullable Object o) {
      return Maps.containsEntryImpl(delegate(), o);
    }

    @Override
    public boolean containsAll(Collection<?> c) {
      return standardContainsAll(c);
    }

    @Override
    public boolean removeAll(Collection<?> c) {