Documentation for url-pattern

Hi, I'm using private bitbucket and url-pattern has to be used.

The example in config-example.json doesn't work for me. I need to customize my own.

But I don't find any document explaining this config. I don't understand the relationship between url, base_url and url-pattern, and what parameters can be used like {path}, {filename}, etc. (is there a {branch}?)

Hope the answer is added into a document so that others can benefit from that.

Thanks