code: public ADDRESST unregisterParticipant(ADDRESST address, EventListener entity) {
  		synchronized (mutex()) {
  			removeListener(address);
  			this.participants.remove(entity.getID(), address);
  		}
  		return address;
  	}
docs: Remove a participant from this repository.
  
  @param address address of a participant to remove from this repository.
  @param entity participant to unmap to the given address.
  @return a.