What should I be putting in "Main assets" when submitting an editor extension asset?

My asset consists of code files only, no art, no prefabs, etc. They said to use what you consider to be the central parts of your asset and so Unity will generate a showcase for those - I’m not sure what “generating a showcase for code files” really means here.

26478-pub.png

Is it even necessary? If so, what should I be putting in it? and can somebody give an example of how these “main assets” would look like on the asset store? is it what appears under the “Contents” section?

Thanks.

So the answer is: None. Don’t put anything.