code: @Override
    public boolean deleteFlowEdge(String edgeId) {
      try {
        rwLock.writeLock().lock();
        return flowEdgeMap.containsKey(edgeId) && deleteFlowEdge(flowEdgeMap.get(edgeId));
      } finally {
        rwLock.writeLock().unlock();
      }
    }
docs: Delete a {@link DataNode} by its identifier
  @param edgeId identifier of the {@link FlowEdge} to be deleted.
  @return true if {@link FlowEdge} is successfully deleted.