public String getConstraintsAsString() {
        return constraintsString;
    }
@Test
    void getConstraintsAsString() {
        OPERATOR operator = OPERATOR.LESS_THAN;
        Object value = 234;
        KiePMMLOperatorValue kiePMMLOperatorValue = new KiePMMLOperatorValue(operator, value);
        String retrieved = kiePMMLOperatorValue.getConstraintsAsString();
        String expected = String.format(VALUE_CONSTRAINT_PATTERN, operator.getOperator(), value);
        assertThat(retrieved).isEqualTo(expected);
    }