knowm/XChange — reverse-engineered prompt

Build me a Java library that gives me one clean, consistent way to work with a lot of crypto exchanges, around 60 or more if possible. I want it to handle the common stuff in the same shape no matter which exchange I use, like getting public market data such as tickers and order books, and also private actions when I provide API credentials, like account balances and trading.

It should be easy to create an exchange client, grab the right service, and make requests without learning a totally different API every time. For exchanges that support real time data, also include websocket streaming so I can subscribe to live trades and order book updates. A smaller set of streaming integrations is fine.

Please make it buildable with Maven, organized so each exchange can have its own implementation behind the shared interface, and include example code for public access, authenticated access, and streaming. If current exchange docs have changed, look them up online and make sensible updates while keeping the API simple.