Make entity fields required by default

[olivier-thatch]

This PR changes how grape-swagger-entity determines if an entity field is required or not:

1. if documentation: { required: true/false } is set, use that
2. otherwise, if if or unless is not null or if expose_nil is false, assume the parameter is not required
3. otherwise, assume the parameter is required

This is consistent with how grape-entity renders fields: fields are always exposed unless if or unless is provided (cf. https://github.com/ruby-grape/grape-entity?tab=readme-ov-file#conditional-exposure).

Closes #80.

This is probably a breaking change, so I understand if you don't want to merge this as is, but it would be nice to be able to opt into this behavior.

[numbata]

Thanks a lot for this contribution, @olivier-thatch! The changes look generally good, and I appreciate that you not only highlighted this problem, but also suggested a solution. I do have some thoughts on a potential simplification in one of the methods, which I've detailed in a comment below.

[olivier-thatch]

I've updated the PR to account for another case of conditional exposure: expose_nil: false (cf. docs).

[olivier-thatch]

Hi @numbata, any chance this could get merged and released sometimes soon?

[dblock]

I'll merge this, open an issue for a release, can do if we don't see @numbata for a while.

[numbata]

I'll do release tomorrow (if that's okay), but I think we should add a bit words into the CHANGELOG or README, as this PR changes existing behavior.
Even though the change is positive, it could be considered breaking in some cases.

[dblock]

@numbata Good call, def increment the version accordingly.

[numbata]

@dblock I’ve added an UPGRADING.md file here.
Let me know if anything should be changed, improved, or added.

[dblock]

LGTM! Release it

[numbata]

@olivier-thatch FYI: Released! 🎉

• https://github.com/ruby-grape/grape-swagger-entity/releases/tag/v0.7.0
• https://rubygems.org/gems/grape-swagger-entity/versions/0.7.0

[olivier-thatch]

Thank you both! 🎉