What does this mean in this java code snippet regarding the filters?

What does this mean in this java code snippet regarding the filters?
public long[] getNodeChildren(long nodeId) throws ManagementSupportException {
            TEServiceStub.GetNodeChildren request = new TEServiceStub.GetNodeChildren();
            TEServiceStub.NodesKey key = new TEServiceStub.NodesKey();
            key.setNodeID(nodeId);
            //here, we can set a filter here, but what to set ? null.
            //filters are not implemented yet
            key.setFilters(null);
            request.setKey(key);

            TEServiceStub.GetNodeChildrenResponse response = null;
            try {
                  response = stub.getNodeChildren(request);
            } catch (RemoteException e) {
                  logger.warn("Fail to call TEService :" + e);
                  throw new ManagementSupportException("Fail to call TEService :" + e);
            }

            if(!response.getStatus().getSuccess()) {
                  logger.warn("TEService return failure while call getNodeChildren()");
                  throw new ManagementSupportException("TEService return failure while call getNodeChildren()");
            }
            return response.getChildNodeIDs().getValue();
      }