/guava/guava/src/com/google/common/graph/DirectedMultiNetworkConnections.java
if ( successors == null ) { successors = HashMultiset.create ( outEdgeMap.values ( ) ) ; successorsReference = new SoftReference<> ( successors ) ; }
@Override public Set<N> successors() { return Collections.unmodifiableSet(successorsMultiset().elementSet()); } private Multiset<N> successorsMultiset() { Multiset<N> successors = getReference(successorsReference); <extra_id_0> return successors; } @Override public Set<E> edgesConnecting(N node) { return new MultiEdgesConnecting<E>(outEdgeMap, node) { @Override