Implement equals() and hashCode() for data models

[derekyyyan]

Hi,

I've noticed that the data models don't have equals() and hashCode() implemented, which has caused issues with my own unit tests. I was able to get around the issue by extending these classes and implementing my own equals() and hashCode(), but such a solution wasn't ideal.

I believe having equals() and hashCode() implemented for these data models will make development more intuitive and convenient for people using this library.

Thanks!

[jflefebvre06]

Hello @gmessner

Do you know the lombock project ? It can help you

[gmessner]

@jflefebvre06 This issue is was submitted by my request by someone else that mentioned Lombok, please read my response to that: https://github.com/gitlab4j/gitlab4j-api/issues/271#issuecomment-572858974