notes/pl/java/tools/decompile/intellij-java-decompiler.txt

https://github.com/JetBrains/intellij-community/tree/master/plugins/java-decompiler/engine
https://github.com/fesh0r/fernflower

https://stackoverflow.com/questions/28389006/how-to-decompile-to-java-files-intellij-idea