Context

Currently the different tests in the code base use MockRestServiceServer from spring framework as well as RestDriver (same named library).
RestDriver is based on jetty 9 which is incompatible with the spring framework 6.
For moving forward we need to avoid direct relation on java.servlet based packages.

Possible Implementation

Keeping #837 in mind it's better to avoid usage of MockRestServiceServer in the tests, so we can use use MockWebServer from OkHttp.
The library is independent from javax.server namespace problems, as well as providing good enough level control.

Another option would be to wait for wiremock 3 release (beta version of wire mock 3 already available, though not sure if that would be possible without simultaneous migration of the spring framework to version 6 due to JEE api changes)