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This is a question from a change [1] which adds a new changes-before 
filter to the servers, os-instance-actions and os-migrations APIs.

For context, the os-instance-actions API stopped accepting undefined 
query parameters in 2.58 when we added paging support.

The os-migrations API stopped allowing undefined query parameters in 
2.59 when we added paging support.

The open question on the review is if we should change GET /servers and 
GET /servers/detail to stop allowing undefined query parameters starting 
with microversion 2.66 [2]. Apparently when we added support for 2.5 and 
2.26 for listing servers we didn't think about this. It means that a 
user can specify a query parameter, documented in the API reference, but 
with an older microversion and it will be silently ignored. That is 
backward compatible but confusing from an end user perspective since it 
would appear to them that the filter is not being applied, when it fact 
it would be if they used the correct microversion.

So do we want to start enforcing query parameters when listing servers 
to our defined list with microversion 2.66 or just continue to silently 
ignore them if used incorrectly?

Note that starting in Rocky, the Neutron API will start rejecting 
unknown query parameteres [3] if the filter-validation extension is 
enabled (since Neutron doesn't use microversions). So there is some 
precedent in OpenStack for starting to enforce query parameters.

[1] https://review.openstack.org/#/c/599276/
[2] 
https://review.openstack.org/#/c/599276/23/nova/api/openstack/compute/schemas/servers.py
[3] https://docs.openstack.org/releasenotes/neutron/rocky.html#upgrade-notes

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Thanks,

Matt