OAuth2AuthorizationRequest is not extendable

[aranoverse]

Describe the bug

OAuth2AuthorizationRequest is not extendable

To Reproduce

the following is declaration of AuthorizationRequestRepository and OAuth2AuthorizationRequest is final class.
it means that we can not create new CustomOAuth2AuthorizationRequest which extends OAuth2AuthorizationRequest

  public interface AuthorizationRequestRepository <T extends OAuth2AuthorizationRequest> 

Expected behavior

OAuth2AuthorizationRequest should not be final class

[sjohnr]

Closing per this comment.