Importing data via Administration>Entity Inspector>Import. How does It work?

How can I use this thing? Does it import data into db? Files of which type should I use? How do they look like inside, what is their stricture?
I export data in JSON file, but when I give the same file to import, I get error.

Screen
14
Error
25

Hi,
can you please provide a small demo project that demonstrates the issue? It is hard to guess what is the entity structure, what platform version do you use and what is the reason for the error you get.

You can pack the project using the zipProject gradle task and attach the archive here.