How to get all possible fields when importing via JSON?

[Karlovsky120]

I'm migrating to JIRA from another issue tracker. It seems that JSON import can import everything I'm interested in, but I'm unsure of the format of the JSON.

Is there an example reference JSON that uses every possible field for every possible entity so I know what I'm working with?
Is there some other source of information from which I can unambiguously determine how to structure the import JSON?

The best I could find is this article:
https://confluence.atlassian.com/adminjiraserver/importing-data-from-json-938847609.html

But I'm not sure if it's extensive.