How to use Java API?

I found this Java API: https://developer.atlassian.com/server/bitbucket/reference/java-api/
but I couldn’t find any examples on how to use it such as setting up authentication, and doing some basic tasks.
Any help is appreciated. Thanks in advance.

Howdy, can you explain what you mean by those two questions? I’m happy to explain a bit.

What do you need to use authentication for? I’ll try to write an example based on what you’re saying.

What sort of basic tasks are you trying to do?

Like for example what class would I use to pull all projects and then get a list of all repos per project if that makes sense done using the Java API.
Do I need to setup some initial connection to the onprem Bitbucket Server and how would I do that through the code?
Thanks.

You need to create a bitbucket p2 plugin.