code: public synchronized void addToJoinDoNotCancel(ISynchronizationPoint<? extends TError> sp) {
  		nbToJoin++;
  		sp.listenInline(new Runnable() {
  			@Override
  			public void run() {
  				if (sp.hasError())
  					error(sp.getError());
  				else
  					joined();
  			}
  		});
  		if (Threading.debugSynchronization) ThreadingDebugHelper.registerJoin(this, sp);
  	}
docs: Similar to addToJoin, but in case the synchronization point is cancelled,
  it is simply consider as done, and do not cancel this JoinPoint.