Consider using JavaPoet or JavaWriter to create java sources.

[JavaPoet](https://github.com/square/javapoet) and its predecessor, [JavaWriter](https://github.com/square/javapoet/tree/javawriter_2), are two libraries developed by Square that make writing Java files a bit easier and a lot more readable. JavaPoet is preferred but I found JavaWriter to be more a bit more flexible.
