onNewSubscription(roomId) {
    const subMessageId = this.publisher.sendSubscription(roomId);

    debug(
      "[%s] Broadcasting new realtime subscription on room %s (message: %d)",
      this.nodeId,
      roomId,
      subMessageId,
    );

    this.fullState.addRealtimeSubscription(roomId, this.nodeId, subMessageId);
  }
Triggered on a new realtime subscription

@param  {string} roomId
@return {void}