* @param caller The graph that is calling, so that if an edge must be created, it knows what type to make,
* and what graph to add it to
* @return The edge that is assured to be in the graph
*/
protected TestbedEdge ensureEdgeExists(Agent src, Agent sink, JungAdapterGraph<Agent, TestbedEdge> caller) {
TestbedEdge edge = caller.findEdge(src, sink);
if (edge == null) {
edge = newEdge(src, sink, caller);
caller.addEdge(edge, src, sink);
}
return edge;