code: public SubscriberEndpoint getNewOrExistingSubscriber(String senderPublicId) {
  		SubscriberEndpoint subscriberEndpoint = new SubscriberEndpoint(webParticipant, this, senderPublicId,
  				this.getPipeline(), this.openviduConfig);
  
  		SubscriberEndpoint existingSendingEndpoint = this.subscribers.putIfAbsent(senderPublicId, subscriberEndpoint);
  		if (existingSendingEndpoint != null) {
  			subscriberEndpoint = existingSendingEndpoint;
  			log.trace("PARTICIPANT {}: Already exists a subscriber endpoint to user {}", this.getParticipantPublicId(),
  					senderPublicId);
  		} else {
  			log.debug("PARTICIPANT {}: New subscriber endpoint to user {}", this.getParticipantPublicId(),
  					senderPublicId);
  		}
  
  		return subscriberEndpoint;
  	}
docs: Returns a {@link SubscriberEndpoint} for the given participant public id. The
  endpoint is created if not found.
  
  @param remotePublicId id of another user
  @return the endpoint instance