Group Reconciliation fails on a controller node restart with ovs2.3.2 switch

Steps to reproduce:

1. Configure a group(either FF/Indirect/ALL/SELECT) on the controller using POSTMAN

2. Connect an ovs2.3.2 switch. The switch reflects the flow due to reconciliation

3. Start the wireshark on the 6633 port and Restart the controller

4. We see OFPGMFC_GROUP_EXISTS error for the group_mod on the wire.

On analysing the issue, it happens due to the fact that by the Openflow specifications(both 1.3.1 and 1.3.5):

"For add requests (OFPGC_ADD), if a group entry with the specified group identifier already resides in
the group table, then the switch must refuse to add the group entry and must send an ofp_error_msg
with OFPET_GROUP_MOD_FAILED type and OFPGMFC_GROUP_EXISTS code."

(pg 37/47)