ExpressionJwtGrantedAuthoritiesConverter is undocumented

[wilkinsona]

Describe the bug

There's no reference documentation for ExpressionJwtGrantedAuthoritiesConverter. I had hoped to find something in https://docs.spring.io/spring-security/reference/servlet/oauth2/resource-server/jwt.html#oauth2resourceserver-jwt-authorization-extraction.

To Reproduce

N/A

Expected behavior
The reference documentation describes ExpressionJwtGrantedAuthoritiesConverter and when and how it should typically be used. Some more details on how it "can be used in combination with a DelegatingJwtGrantedAuthoritiesConverter" would also be beneficial.

Sample

N/A