Convert small Python web application into Java 17 + Spring

We need to convert the localstripe project (Test server for integration with Stripe) which is coded in Python into Java 17 / Spring Boot. Code is available here: https://github.com/adrienverge/localstripe

localstripe has a few endpoints available that must be converted into a Spring Boot application. localstripe is stateful, which is pretty handy to test the integration of an application with Stripe, and this behaviour must be reproduced.

Here are a few specifications of what we expect:
- Java version 17 with use of JPMS;
- Spring Boot version 3
- No database to integrate with, data should be stored in memory only;
- Junit tests
- Integration tests with the actual Python localstripe to compare results and follow evolutions