### Question:
SignalRef implements BPMNProperty { public SignalRef() { this(""); } SignalRef();  SignalRef(final @MapsTo("value") String value); String getValue(); void setValue(final String value); @Override int hashCode(); @Override boolean equals(Object o);  }### Answer:
@Test public void testSignalRef() { assertValidExpression(EMPTY_REF); assertValidExpression(VALID_STATIC_REF); assertValidExpression(VALID_MVEL_REF_1); assertValidExpression(VALID_MVEL_REF_2); assertValidExpression(VALID_MVEL_COMPLEX_REF_1); assertValidExpression(VALID_MVEL_COMPLEX_REF_2); assertValidExpression(VALID_MVEL_COMPLEX_PARAM_REF_1); assertValidExpression(VALID_MVEL_COMPLEX_PARAM_REF_2); assertValidExpression(VALID_COMBINATION_1); assertValidExpression(VALID_COMBINATION_2); assertValidExpression(VALID_COMBINATION_3); assertValidExpression(VALID_COMBINATION_4); assertValidExpression(VALID_EXPRESSION); assertInvalidExpression(INVALID_STATIC_REF); assertInvalidExpression(INVALID_MVEL_REF); assertInvalidExpression(INVALID_MVEL_COMPLEX_REF_1); assertInvalidExpression(INVALID_MVEL_COMPLEX_REF_2); assertInvalidExpression(INVALID_MVEL_COMPLEX_REF_3); assertInvalidExpression(INVALID_MVEL_COMPLEX_REF_4); assertInvalidExpression(INVALID_MVEL_PARAM_COMPLEX_REF_1); assertInvalidExpression(INVALID_MVEL_PARAM_COMPLEX_REF_2); assertInvalidExpression(INVALID_MVEL_PARAM_COMPLEX_REF_3); assertInvalidExpression(INVALID_MVEL_PARAM_COMPLEX_REF_4); assertInvalidExpression(INVALID_MVEL_PARAM_COMPLEX_REF_5); assertInvalidExpression(INVALID_MVEL_PARAM_COMPLEX_REF_6); assertInvalidExpression(INVALID_COMBINATION_1); assertInvalidExpression(INVALID_COMBINATION_2); assertInvalidExpression(INVALID_COMBINATION_3); assertInvalidExpression(INVALID_COMBINATION_4); }