MET-5697 refactor and add unit tests #946

Job	Run time
ci / build	6m 55s
docker-build_metis-core / docker-build-push	1m 18s
docker-build_metis-authentication / docker-build-push	1m 10s
deploy-artifacts / deploy_libraries	0s
docker-build_metis-dereference / docker-build-push	1m 1s
docker-build_metis-repository / docker-build-push	1m 6s
	11m 30s

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