[on_and_off]

the java compiler does not do that unfortunately,

Kotlin would do what they call a 'smartcast' : ie if you did an instanceof if the if, in the corresponding {}closure you know the type of this object.

The whole code is probably unmaintanable for anybody other than it's original writer (and even for him, there must be a limit to how much code you can fit in your head).

I would love to work for Telegram, it is one of the products I use daily .. but if I had to handle this codebase, it would be a rare case of 'total rewrite or I am out'.

Incidentally, it looks like they are going to do this full rewrite. Telegram seems to have acqui-hired the creators of Telegram X and are prepping it up as a replacement.