Umlet 15.1 now generates UML class diagrams from code.
You can give it a file or directory and will generate class elements in a grid like diagram with no relations.
The generation stops if Umlet encounters an enum, which is a bit of a bummer, but still this can give your a nice headstart if you already have some code.
This release is (maybe even more importantly) also reported to solve a nasty bug that crashed Umlet 15.0 on some actions.