L2GW: remove openstack l2-gateway configuration does not remove from restconf

when creating HW vtep configuration in openstack:
create vxlan netwotk
neutron l2-gateway-create -device name=<switch_name> interface_names=<vtep port>
neutron l2-gateway-connection-create --default-segmentation-id <the vlan of the vlan network> <l2-gateway name> <vxlan network name>

And then running
ovsdv-client dump <switch-ip>

I can see the the switch ports recieve the currect vlan (<the vlan of the vlan network>), for example:

Physical_Port table
_uuid description name port_fault_status vlan_bindings vlan_stats
------------------------------------ ----------- ----------------------------- ----------------- ------------------------------------------ ----------
e30ba015-c068-41ad-a1fb-41758ee3b092 "" "Ten-GigabitEthernet1/0/25:1" [UP]

{}
508fb6af-2ece-498e-b894-82164980e1c2 "" "Ten-GigabitEthernet1/0/5:1" [UP] {} {}
793ecd9d-7588-4384-a7d1-55c19cb1e2d6 "" "Ten-GigabitEthernet1/0/7:2" [UP] {} {}

when I try to re-run this scenario, including trying to configure another switch connected to another vlan network, the vlan column is not configured.
Attaching “good” and “bad” output of ovsdb-client dump.