During Deletion of Instances and Network. Flows are not getting removed from table:20 and table:90

ODL Version : distribution-karaf-0.5.2-Boron-SR2

Openstack Version : mitaka

Setup Details : 1 Control Node + 2 Compute Nodes + 3 ODL Nodes

Steps to Reproduce :
1. ./unstack Control Node and Compute nodes
2. Delete logs, snapshot and data from all three ODL nodes
3. Start ./bin/karaf and installing "odl-ovsdb-openstack"
4. Check cluster is formed. And check network topology is initiated
5. ./stack up Control Node and Compute Nodes
6. Check initial flows in control node and compute nodes.
7. Create a Network and 5 instances. And check ip address are assigned for all the instances.
8. Check control node and compute nodes flows for the created network and instances.
9. Delete Instances and network.
10. Check flows for removed network and instances in the control node and compute nodes. We observed flows are not removed and below are our observation:

Observations:

1) When all instances are deleted, flows are not getting removed from table:20, table:90. In both control node and compute nodes
2) When a network is deleted, dhcp flows are not getting removed from control node but it removed from compute nodes. And in compute nodes "ARP flows" from instances are not getting removed.
3) Some Instances "ip flows" are not getting removed in table:90. In both control and compute nodes.
4) We have observed above issues in both "Normal" and "Failover scenario"

The same above issue is reproduced in CSIT, below is the link,

https://logs.opendaylight.org/releng/jenkins092/netvirt-legacy-csit-3node-openstack-mitaka-upstream-boron/39/archives/log.html.gz#s1-s3-s1-t43-k3-k1-k2-k1-k16-k3

Please find attached files for Karaf logs and Flow details.