Allow for multiple Jwt to GrantedAuthorizies converters #7596

[rolaca11]

Resolution of gh-7596.

In this PR, I introduce a way to have multiple granted authority converters inspect the incoming Jwt token and return the union of authorities returned by those converters.

This PR also refactors the OAuth2ResourceServerConfigurer to make better use of the newly introduced way of managing aforementioned converters.

[jzheaux]

@rolaca11 would you be able to adjust this PR to conform to #7596 (comment)

[rolaca11]

Yes, I'll make time for it this evening.

[jzheaux]

Thanks, @rolaca11! Will you please take a look at https://github.com/spring-projects/spring-security/blob/master/oauth2/oauth2-core/src/main/java/org/springframework/security/oauth2/core/DelegatingOAuth2TokenValidator.java and emulate that contract, for consistency?

Namely, please have a Collection constructor and varargs constructor, please remove the mutator methods, and please add some JavaDoc, including an @author tag, if you'd like.

[jzheaux]

Thanks, @rolaca11! I've left just a bit more feedback inline.

[rolaca11]

Of course, sorry for the lot of feedback iterations, I'll do my best

[jzheaux]

Sorry this fell off my radar, @rolaca11. I just left a bit more feedback.

If you like, I'd be happy to make the remaining changes listed.

Or, if you still are able to complete the PR, please also squash your commits down to one commit that includes Closes gh-7596 at the end of the commit message.

[rolaca11]

This is my first time squashing commits of a branch, so I might have messed up somewhere along the way. Can you please help me make sure everything is correct?

[jzheaux]

Thanks, @rolaca11! This is now merged into master.

I've also contributed a polish commit of b0d4e50 to bring the contribution in line with Spring Security conventions.

[NeluAkejelu]

Great! Thanks @jzheaux @rolaca11 👍