code: @Override
    public Set<FlowEdge> getEdges(DataNode node) {
      try {
        rwLock.readLock().lock();
        return (node != null) ? this.nodesToEdges.getOrDefault(node, null) : null;
      } finally {
        rwLock.readLock().unlock();
      }
    }
docs: Get the set of edges adjacent to a {@link DataNode}
  @param node {@link DataNode}
  @return Set of {@link FlowEdge}s adjacent to the node.