You should get into enterprise Java. Too inscrutable to change, to complex to replace. Every now and then they try, manage to replace 4% of the functionality whatever platform or design pattern is popular at the time before running out of budget, and now the system is an even more byzantine Cronenberg.
I hear, every once in a while you can spot a rare IllegalStateException("Killll mmeeeee...."); being thrown in the logs.
Things I wish a legacy codebase had: documentation (maybe with history of major changes in its lifetime), tests, up to date comments, and modular design that allows for deprecating/replacing itself part by part to a new system.