code: public static <V> Set<V> getOutgoingVertices(DirectedGraph<V, DefaultEdge> graph, V source) {
          Set<DefaultEdge> edges = graph.outgoingEdgesOf(source);
          Set<V> targets = new LinkedHashSet<V>();
          for (DefaultEdge edge : edges) {
              targets.add(graph.getEdgeTarget(edge));
          }
          return targets;
      }
docs: Fetch all of the dependencies of the given source vertex
  @return mutable snapshot of the target vertices of all outgoing edges