presto-main/src/main/java/io/prestosql/util/GraphvizPrinter.java/EdgePrinter/visitRemoteSource
class EdgePrinter:        @Override
        public Void visitRemoteSource(RemoteSourceNode node, Void context)
        {
            for (PlanFragmentId planFragmentId : node.getSourceFragmentIds()) {
                PlanFragment target = fragmentsById.get(planFragmentId);
                printEdge(node, target.getRoot());
            }

            return null;
        }