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