To start this, first build the sibling modules then use
mvn clean install exec:java
In this folder, and open http://localhost:8080 - which might require logging in at http://localhost:8080/system/console first.
This should redirect you to a JSON content page, currently http://localhost:8080/content.rakam.json
The standard MAVEN_OPTS environment variable can be used to setup debugging, as the above does not fork and starts the application with the Maven JVM.
After that...well, the API is supposed to be discoverable so you should find your way!
To activate debugging, use the standard MAVEN_OPTS - the Java code is started directly in the Maven process.
The /content/articles subtree is where the most interesting content is, for now.
The test content uses com.adobe.aem.guides:aem-guides-wknd.ui.content.sample which is MIT licensed. Minimal “fake” JCR nodetype definitions are used to allow this content to load, as we don't really care about the details of these node types besides their names.