@Test
    void testOrEmptyNot() {
        final ExpressionOperator expressionOperator = ExpressionOperator.builder()
                .op(Op.OR)
                .addOperator(ExpressionOperator.builder().op(Op.NOT).build())
                .addOperator(ExpressionOperator.builder().op(Op.NOT).build())
                .build();

        final Condition condition = doTest(expressionOperator);

        assertThat(condition).isEqualTo(DSL.noCondition());
    }
This ought to behave in a consistent way with ExpressionMatcher
stroom-db-util/src/test/java/stroom/db/util/TestCommonExpressionMapper.java