Prefer mapping without version for requests without a version #35237
Description
For requests without a version, all mappings are considered a match. After the sort, the mapping with the highest (most recent) version is selected as the best match currently.
It would makes sense to match requests without a version to mappings without a version. This would support cases where versioning is not introduced from the beginning, but gradually and selectively, and requests without a version are from clients that haven't started upgraded and are not sending a version.
Alternatively, it is also possible for an application to set a defaultVersion in the configuration for more control of how to interpret unversioned requests.