Decompile inner classes

How to decompile inner classes in one java file with main with CFR?
I remember in old versions inner classes was decompiled in one file with main class.

Start by reproducing the reported behavior with CFR and a Java file containing inner classes and a main class. Compare the current output with the described older behavior; done means determining whether inner classes should be emitted in one file and documenting or fixing the observed result.

Written by the indexing model from the issue text.