docs: private InterproceduralCallGraphVertex findVertex(XMethod xmethod) {
          InterproceduralCallGraphVertex vertex;
          vertex = callGraph.lookupVertex(xmethod.getMethodDescriptor());
          if (vertex == null) {
              vertex = new InterproceduralCallGraphVertex();
              vertex.setXmethod(xmethod);
              callGraph.addVertex(vertex);
          }
          return vertex;
      }