code: public static IHttpCredentialsPlugin GetDrpcHttpCredentialsPlugin(Map conf) {
          String klassName = (String) conf.get(Config.DRPC_HTTP_CREDS_PLUGIN);
          return AuthUtils.GetHttpCredentialsPlugin(conf, klassName);
      }
docs: Construct an HttpServletRequest credential plugin specified by the DRPC storm configuration
  
  @param conf storm configuration
  @return the plugin