DirectedMultiNetworkConnections.java 文件源码

private Multiset<N> successorsMultiset() {
  Multiset<N> successors = getReference(successorsReference);
  if (successors == null) {
    successors = HashMultiset.create(outEdgeMap.values());
    successorsReference = new SoftReference<Multiset<N>>(successors);
  }
  return successors;
}