code: function header (request) {
  
      var headers = assign({}, Http.headers.common,
          !request.crossOrigin ? Http.headers.custom : {},
          Http.headers[toLower(request.method)]
      );
  
      each(headers, function (value, name) {
          if (!request.headers.has(name)) {
              request.headers.set(name, value);
          }
      });
  
  }
docs: Header Interceptor.