mod-spring-sample POST /_/tenant fails with 404 Not found

How to reproduce:

1. mvn clean package
2. Either
   a) java -jar target/mod-spring-sample-1.0.0-SNAPSHOT.jar
   or
   b) docker build -t mod-spring-sample . and docker run -p 9000:9000 mod-spring-sample
3. curl -w"\n" -sS -D - -HContent-type:application/json -Hx-okapi-url-to:http://localhost:9130/ -Hx-okapi-tenant:diku -d '{"module_to": "1.0.0"}' http://localhost:9000/_/tenant

Expected result:

Module creates database tables for tenant diku.

Actual result:

HTTP/1.1 404
Vary: Origin
Vary: Access-Control-Request-Method
Vary: Access-Control-Request-Headers
Content-Type: application/json
Transfer-Encoding: chunked
Date: Mon, 11 Apr 2022 09:27:50 GMT{"timestamp":"2022-04-11T09:27:50.473+00:00","status":404,"error":"Not Found","message":"","path":"/_/tenant"}

Credits:

This issue has been reported on https://discuss.folio.org and FOLIO's #support Slack channel.

Task:

Please expand the repository's README how to use and run, and fix the code if needed.

Or archive (FOLIO-1838 and FOLIO-1710) this repository if it is no longer supported.