Implement equals for the ImmutableMetadata object

[thomaspoignant]

Context

When working with an ImmutableMetadata it is hard to write tests because we cannot compare a FlagEvaluationDetails anymore.

String flagKey = "bool_targeting_match";
FlagEvaluationDetails expected = FlagEvaluationDetails.builder()
        .reason(Reason.ERROR.toString())
        .value(false)
        .errorCode(ErrorCode.GENERAL)
        .errorMessage("impossible to contact GO Feature Flag relay proxy instance")
        .flagMetadata(ImmutableMetadata.builder().build())
        .build();
FlagEvaluationDetails<Boolean> got = goffClient.getBooleanDetails(flagKey, false, defaultEvaluationContext);
assertEquals(expected, got);

The JUNIT method assertEquals is comparing the reference of the object.

Expected behavior

We should be able to use assertEquals for the whole FlagEvaluationDetails object.
For this we should probably implement the equals() method in the ImmutableMetadata object.

[justinabrahms]

💯

[toddbaert]

Should we consider other types that could benefit from this as well?. I don't think it's needed for EvaluationContext types, but I think it would be useful for Structure.

[thomaspoignant]

Yes this is probably something we should look at.

I haven't seen other problem for now but I haven't test with Structure I will check it

[thomaspoignant]

@toddbaert I've looked at Structure and it works already because we have the annotation in the ImmutableStructure.

I think we are good now, except if we want to introduce it for the EvaluationContext too.

java-sdk/src/main/java/dev/openfeature/sdk/ImmutableStructure.java

Line 19 in ef199b9

@EqualsAndHashCode

[toddbaert]

@toddbaert I've looked at Structure and it works already because we have the annotation in the ImmutableStructure.

I think we are good now, except if we want to introduce it for the EvaluationContext too.

java-sdk/src/main/java/dev/openfeature/sdk/ImmutableStructure.java

Line 19 in ef199b9

@EqualsAndHashCode

Thanks @thomaspoignant !

I could see some use-cases for hasing/comparing EvaluationContext, but I think they are limited. The one that comes to mind immediately is for comparing it in a provider, for some kind of caching, maybe. I'll think about it more but we can always address it in a new issue.