Running the testcase with recent qtbase started giving errors:

QCRITICAL: tst_OAuth2::setSslConfig() Could not find certificate:  "/dev-qtnetworkauth/tests/auto/oauth2/certs/selfsigned-server.crt"

The immediate reason seems to be that this produces an invalid QDateTime for certificate's expiration time:
https://code.qt.io/cgit/qt/qtbase.git/tree/src/plugins/tls/shared/qasn1element.cpp#n248
The datetime in question is: 99991231235959Z, which is at the edge of supported datetimes.

Main question is that has something changed and such datetime doesn't work anymore, or should qtnetworkauth just use certificates with more mundane expiration time (ie. not in year 9999)