Document how a network driver plugin confirms exposed ports

In this example request, I see the information needed to expose container ports in the undocumented 'Options' keys. I cannot tell how I would tell the docker daemon that the ports had been exposed so that they will be displayed, for example in docker ps.

How can a docker network plugin return the port mapping so that it appears in docker ps and docker inspect?

{'EndpointID': 'd2cd7f8fa079d4af8450985a76bcd82cac268da469ceed3366f2fba373524bda',
 'NetworkID': 'de18f6d7edf488138815ae7fc8412be6ad88774e5e5ee041232fc8a96eff59e7',
 'Options': {'com.docker.network.endpoint.exposedports': [{'Port': 80,
                                                           'Proto': 6}],
             'com.docker.network.portmap': [{'HostIP': '',
                                             'HostPort': 0,
                                             'HostPortEnd': 0,
                                             'IP': '',
                                             'Port': 80,
                                             'Proto': 6}]},
 'SandboxKey': '/var/run/docker/netns/7541c34f2dc7'}

Start with the network-plugin example and the Options keys shown in the issue, then compare the behavior of docker ps and docker inspect. Document how a plugin confirms exposed ports and returns the port mapping, including the expected result in both commands; no target file or test is named.