Attempt to authorize or re-authorize (if required) the client identified by the provided clientRegistrationId .

Attempt to authorize or re-authorize (if required) the client identified by the provided clientRegistrationId . Implementations must return null if authorization is not supported for the specified client, e.g. the associated OAuth2AuthorizedClientProvider (s) does not support the authorization grant type configured for the client. In the case of re-authorization, implementations must return the provided authorized client if re-authorization is not supported for the client OR is not required, e.g. a refresh token is not available OR the access token is not expired.