code: static boolean containsAllImpl(Collection<?> self, Collection<?> c) {
      for (Object o : c) {
        if (!self.contains(o)) {
          return false;
        }
      }
      return true;
    }
docs: Returns {@code true} if the collection {@code self} contains all of the elements in the
  collection {@code c}.
  
  <p>This method iterates over the specified collection {@code c}, checking each element returned
  by the iterator in turn to see if it is contained in the specified collection {@code self}. If
  all elements are so contained, {@code true} is returned, otherwise {@code false}.
  
  @param self a collection which might contain all elements in {@code c}
  @param c a collection whose elements might be contained by {@code self}