public boolean addAll(final Collection<? extends Integer> coll)
    {
        boolean added = false;

        for (final Integer value : coll)
        {
            added |= add(value);
        }

        return added;
    }
@Test
    void addingEqualSetDoesNothing()
    {
        addTwoElements(testSet);

        final IntHashSet equal = new IntHashSet(100);

        addTwoElements(equal);

        final HashSet<Integer> equalCollection = new HashSet<>(equal);

        assertFalse(testSet.addAll(equal));
        assertFalse(testSet.addAll(equalCollection));
        assertContainsElements(testSet);
    }