question: private String generateCHash ( String algorithm , OAuth2Request request , OAuth2ProviderSettings providerSettings ) throws ServerException { final AuthorizationCode authorizationCode = request . getToken ( AuthorizationCode . class ) ; if ( authorizationCode == null ) { logger . message ( "c_hash generation requires an existing code." ) ; return null ; } final String codeValue = authorizationCode . getTokenId ( ) ; return generateHash ( algorithm , codeValue , providerSettings ) ; }
target:  For c_hash, used when code and id_token exist in scope.