sendDocumentNotification(rooms, notification) {
    return this.send("DocumentNotification", {
      action: notification.action,
      collection: notification.collection,
      controller: notification.controller,
      index: notification.index,
      protocol: notification.protocol,
      requestId: notification.requestId,
      result: JSON.stringify(notification.result),
      rooms,
      scope: notification.scope,
      status: notification.status,
      timestamp: notification.timestamp,
      volatile: JSON.stringify(notification.volatile),
    });
  }
Publishes an event telling that a document notification must be
propagated

@param  {Array.<string>} rooms - Koncorde rooms
@param  {DocumentNotification} notification
@return {Long} Id of the message sent to other nodes