code: public static boolean isAuthorizedGrantTypeForService(final J2EContext context, final OAuthRegisteredService registeredService) {
          return isAuthorizedGrantTypeForService(
              context.getRequestParameter(OAuth20Constants.GRANT_TYPE),
              registeredService);
      }
docs: Is authorized grant type for service?
  
  @param context           the context
  @param registeredService the registered service
  @return true/false