The code Java one of the most common and robust and well known open source codes in the history of mankind.
Java is the perfect language for mediocre programmers. It's easy to find programmers who can produce working code, a bit like Visual Basic if you knew it... Ask in the developers forums what they think about Java, so many programmers hate it.
There's a lot of bad code but it's not a problem because Java allows you to produce bad code that you can't do in C and C++.
But Java is really easy to make and maintain extremely large enterprise applications, that's why it's popular and many enterprise projects are done in Java but many enterprise projects were done in Visual Basic too, no it's not a reference...