Comment 11 for bug 1705755

just a data point:

networking-midonet has an extension [1], which currently relies on neutronclient's "extra arguments" feature. [2]
in this particular case, it doesn't need to be "extra arguments" though.
ie. there's no problem to implement it explicitly in osc. (if it's ok for osc folks)

[1] https://docs.openstack.org/networking-midonet/latest/reference/specs/mitaka/bgp-speaker-router-insertion.html#other-end-user-impact
[2] https://docs.openstack.org/python-neutronclient/latest/cli/neutron.html#cli-extra-arguments