code: function(crypto, userId) {
          const wireContent = this.getWireContent();
          return crypto.requestRoomKey({
              algorithm: wireContent.algorithm,
              room_id: this.getRoomId(),
              session_id: wireContent.session_id,
              sender_key: wireContent.sender_key,
          }, this.getKeyRequestRecipients(userId), true);
      }
docs: Cancel any room key request for this event and resend another.
  
  @param {module:crypto} crypto crypto module
  @param {string} userId the user who received this event
  
  @returns {Promise} a promise that resolves when the request is queued