public boolean isContainNullElements()
    {
        return containNullElements;
    }
@Test
    public void testIsContainNullElements()
    {
        int elementCount = 100;
        TypedSet typedSet = new TypedSet(BIGINT, elementCount, FUNCTION_NAME);
        BlockBuilder blockBuilder = BIGINT.createFixedSizeBlockBuilder(elementCount);
        assertEquals(typedSet.isContainNullElements(), false);
        for (int i = 0; i < elementCount; i++) {
            BIGINT.writeLong(blockBuilder, i);
            assertTrue(typedSet.add(blockBuilder, i), "First add should return true");
            assertFalse(typedSet.add(blockBuilder, i), "Adding an repeat element should return false");
        }
        assertEquals(typedSet.isContainNullElements(), false);
        blockBuilder.appendNull();
        assertTrue(typedSet.add(blockBuilder, blockBuilder.getPositionCount() - 1), "Original null");
        assertFalse(typedSet.add(blockBuilder, blockBuilder.getPositionCount() - 1), "repeat null");
        assertEquals(typedSet.isContainNullElements(), true);
    }