### Question:
ParamValidationError { @Override public int hashCode() { return Objects.hash(this.message); } ParamValidationError(final String message);  ParamValidationError(final String parameterName, final String parameterValue, final String reason); String getMessage(); @Override int hashCode(); @Override boolean equals(final Object obj); @Override String toString();  }### Answer:
@Test public void testEquality() { final ParamValidationError error1 = new ParamValidationError("full message"); final ParamValidationError error2 = new ParamValidationError("full message"); assertThat(error1) .isEqualTo(error2); assertThat(error1.hashCode()) .isEqualTo(error2.hashCode()); }