@Override
    public Object[] toArray() {
        return toArray(new Object[size]);
    }
@Test
    public void testToGenericArraySetsNullAfterLastContainedElement() {
        final OAHashSet<Integer> set = new OAHashSet<>(8);
        populateSet(set, 10);

        final Integer[] setElementsProvided = new Integer[11];
        final Integer[] setElementsReturned = set.toArray(setElementsProvided);
        assertSame(setElementsProvided, setElementsReturned);

        assertNull(setElementsProvided[10]);
    }