From the REST API guide it is not clear how to insert MPLS tags while inserting the flows into switches. The group stats shows the capabilities. So what is the json format for inserting the MPLS tag in the flow and where to do it from the rest API
Please check if you can get some help from HP SDN java API document (hp-sdn-apidoc-2.0.0 ) that comes with SDN Controller.
For e.g. Package com.hp.util.pkt that has classes Mpls, Mpls.Builder and Mpls.Header.