why the deallocate_port_for_instance does not implement under the nova-network situation?(Juno)

[bruce lee]

when I execute the following command:

"# nova --debug interface-detach 44ce8d76-0ee4-4b5d-9da9-ed66d1502f1e df032714-9f78-4261-aea9-ad36c28a7843"

finally,

REQ: curl -i 'http://vip:8774/v2/ef6ebc7aa16648c2a0efb98122628baf/servers/44ce8d76-0ee4-4b5d-9da9-ed66d1502f1e/os-interface/df032714-9f78-4261-aea9-ad36c28a7843' -X DELETE -H "Accept: application/json" -H "User-Agent: python-novaclient" -H "X-Auth-Project-Id: admin" -H "X-Auth-Token: {SHA1}45f08fc94a39d533186b000299888071fa04bb30"
RESP: [202] {'date': 'Mon, 05 Jun 2017 06:59:01 GMT', 'connection': 'keep-alive', 'content-type': 'text/html; charset=UTF-8', 'content-length': '0', 'x-compute-request-id': 'req-03dab655-333d-4225-a4d8-87c7e21ed778'}
RESP BODY: null

However, the interface didn't detached from the instance.

I checked the code, and find that , in "nova\network\api.py"

    # NOTE(danms): Here for neutron compatibility
    def deallocate_port_for_instance(self, context, instance, port_id):
        raise NotImplementedError()

Does it mean this function just for neutron, but why not implement for nova-network component to use?

I used the Juno versio, furthermore I check the github, current code on the master still the same, Thank you very much who give me some idea or advice or reason.