@Test
    void testNullOperator() {
        final ExpressionOperator expressionOperator = null;

        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