ValidationMessage does not implement equals and hashCode

[sideisra]

Hi,

when testing validation logic i recently had the problem that ValidationMessage does not immplement equals and hashCode so that assertions like the following are noct possible:

assertThat(feeValidator.getValidationStatus().getErrorMessages()).containsExactly(ValidationMessage.error(errorMsg));

I think it would be easier to test when ValidationMessage implements these methods.