@ScalarOperator(GREATER_THAN)
    @SqlType(StandardTypes.BOOLEAN)
    public static boolean greaterThan(@SqlType("unknown") boolean left, @SqlType("unknown") boolean right)
    {
        throw new AssertionError("value of unknown type should all be NULL");
    }
@Test
    public void testGreaterThan()
    {
        assertFunction("NULL > NULL", BOOLEAN, null);
    }