@Override
    public GapList<E> copy() {
	    return (GapList<E>) super.copy();
	}
Returns a shallow copy of this <tt>GapList</tt> instance.
(the new list will contain the same elements as the source list, i.e. the elements themselves are not copied).
This method is identical to clone() except that the result is casted to GapList.

@return a copy of this <tt>GapList</tt> instance
jphp-runtime/src/php/runtime/memory/support/GapList.java