Bitbucket 7.21 Plugin - create custom rest endpoint

I need to create a custom rest endpoint in a Bitbucket Plugin (Bitbucket Server 7.21).I didn't find any information, only Chatgpt sad, that I need to add "rest" and "rest-resource" to my atlassian-plugin.xml:

<rest key="rest-module" path="/rest" version="1.0"><description>Custom REST API</description></rest><rest-resource key="my-rest-resource"                   class="com.avono.atlassian.plugins.bitbucket.mooglereview.api.MyRestResource"/>

But it also doesn't work. The url "http://:7990/rest/custom-api/1.0/example" gives me 404 back.

How to register the new api right? How the url would look like?

Thanks in advance.