@qwert_ukg not really sure what you mean - how do you plan on using companion objects?

e.g. I can add separated data class, for private case of

payload

(json prop) (using only in this case) and, in a same time, i can make private companion object inside my class, where i will use this

payload

That doesn’t really clear things up, but, generally speaking you use companion objects to fill in for the lack of

static

in kotlin - to contain functions that don’t care about object state, constant values, etc

i need class for deserialization from string, guess nested class will be better. Just forget about it. As i see, companion should be used for separated declarations ?