Reduce the number of Maven related warnings in the build

[ahus1]

Describe the bug

The following messages appear in the log, and were a distraction when I was fixing other problems with this build. That's why I raise this issue.

Those warning were present multiple times in the output when building the project:

Warning:  Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
Warning:  File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
Warning:  Rule 0: org.apache.maven.plugins.enforcer.RequireFilesExist failed with message:
Some required files are missing:
/home/runner/work/keycloak-quickstarts/keycloak-quickstarts/app-authz-photoz/photoz-restful-api/src/test/resources/quickstart-realm.json
Warning:  JAR will be empty - no content was marked for inclusion!

Version

999-SNAPSHOT

Expected behavior

No response

Actual behavior

No response

How to Reproduce?

No response

Anything else?

No response

[ahus1]

PR merged.