code: private void addEdgesForVertex(Vertex vertex)
      {
          ClassDescriptor cld = vertex.getEnvelope().getClassDescriptor();
          Iterator rdsIter = cld.getObjectReferenceDescriptors(true).iterator();
          while (rdsIter.hasNext())
          {
              ObjectReferenceDescriptor rds = (ObjectReferenceDescriptor) rdsIter.next();
              addObjectReferenceEdges(vertex, rds);
          }
          Iterator cdsIter = cld.getCollectionDescriptors(true).iterator();
          while (cdsIter.hasNext())
          {
              CollectionDescriptor cds = (CollectionDescriptor) cdsIter.next();
              addCollectionEdges(vertex, cds);
          }
      }
docs: Adds all edges for a given object envelope vertex. All edges are
  added to the edgeList map.
  @param vertex the Vertex object to find edges for