code: public void initUpstream()
  	{
  		for (Interaction inter : pe.getParticipantOf())
  		{
  			AbstractNode wrapper = (AbstractNode) graph.getGraphObject(inter);
  
  			if (wrapper == null) continue;
  
  			Edge edge = new EdgeL3(wrapper, this, graph);
  			wrapper.getDownstreamNoInit().add(edge);
  			this.getUpstreamNoInit().add(edge);
  		}
  	}
docs: Binds to upstream interactions.