Data representation is one of the most important things in any kind of app you develop. The most common, classic way to do it is to create a class with all the fields you want to transport, for example User(name, lastName). It's simple and explicit, but hell no, in my current company we don't play that kindergarten bullshit, the only way we know how to do things here is full hardcore. Why would anyone write a class to represent a Song, a Playlist or an Album when you can just use a key-> value map for pretty much everything? Need a list of songs? No problem, use a List<Map<String, String>>, OBVIOUSLY each map is a song. Need a list of playlists? Use a List<List<Map<String, String>>>... Oh wait, need to treat a value as a number and all you have are strings? That's what casting is for, dumbass.

No, seriously, this company is great. I'm staying here forever!