code: public void addDirectedRoute(final TrustGraphNodeId from, final TrustGraphNodeId to) {
          final TrustGraphNode fromNode = nodes.get(from);
          fromNode.getRoutingTable().addNeighbor(to);
      }
docs: create a directed trust link between two nodes. The node with id 'from' will
  trust the node with id 'to'.
  
  Note: Although this is useful for testing adverse conditions,
  relationships must be symmetric for the normal functioning of
  the algorithm.  An advertising node must trust another node to
  send to it, and that same node must trust the sender in order
  to forward the message (find the next hop for the message).
  
  @param from the id of the node that is trusting
  @param to the id of node that is being trused by the node 'from'