code: @Help(help = "Upgrades a VNFR to a defined VNFD in a running NSR with specific id")
    public void upgradeVnfr(final String idNsr, final String idVnfr, final String idVnfd)
        throws SDKException {
      HashMap<String, Serializable> jsonBody = new HashMap<>();
      jsonBody.put("vnfdId", idVnfd);
      String url = idNsr + "/vnfrecords" + "/" + idVnfr + "/upgrade";
      requestPost(url, jsonBody);
    }
docs: Upgrades a VNFR of a defined VNFD in a running NSR.
  
  @param idNsr the ID of the NetworkServiceRecord
  @param idVnfr the ID of the VNFR to be upgraded
  @param idVnfd the VNFD ID to which the VNFR shall be upgraded
  @throws SDKException if the request fails