operational/l3nexthop:l3nexthop refcount is not decremented when extra-route is removed

(a) Create NET1 , NET2.

(b) Create Router R1.                                  

(c ) Add Subnet1,Subnet2 to Router R1.

(d) Associate Router to L3VPN.

(e ) Create Extra-Route on VM1/NET1 .

(f) Ping extra-route from VM2.

(g) When "neutron router-update <router-name> --no-routes" is executed, extra-route is removed.

Extra-route adj is deleted successfully in config/vpn-interface , vpn-interface-op-data , vpn-extraRoute , FIB datastores.

But its not decremented in l3nexthop datastore which stores local next groups for the prefix