Add claim delimiter configuration example in OAuth2 Resource Server JWT documentation

[PatrickWalter214]

Expected Behavior

An example for configuring the claim delimiter is listed in the Extracting Authorities section of the OAuth2 Resource Server JWT documentation.

Current Behavior

The JwtGrantedAuthoritiesConverter has 3 available methods for configuration. But only 2, namely the configuration of the authorities claim and the authorities prefix, are outlined in the documentation.

Context

About a year ago I opened a PR that added the possibility to configure the claim delimiter. Now I would like to outline this configuration option in the Spring documentation. The configuration example I want to add would be the same as in the test of the method, with the relevant lines being:

JwtGrantedAuthoritiesConverter jwtGrantedAuthoritiesConverter = new JwtGrantedAuthoritiesConverter();
jwtGrantedAuthoritiesConverter.setAuthoritiesClaimDelimiter(",");

With this issue I would like to discuss if it is ok to outline this configuration in the documentation.

[jzheaux]

@PatrickWalter214, yes, I think that would be a good addition to the documentation. Would you please add for servlet as well as reactive?