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