Design Compose object in kotlin/Java

I am working with an object with a compose structure as the directories one, when could be directories and files. The mock of the final response is something like:

I have created some data class, Section, with an array of items, and also the could have a children which has a section again.

What I am doing is using hashMaps to build the complex object, but a better option could be use a creational pattern. I don't have enough experience using the creational patterns, and who is the more appropriate for this case.

Thanks for any suggestion in advance.