I tried downloading plantuml with the following documentation:
https://github.com/walkingriver/plant-uml
I a still getting the error invalid or corrupt jarfile. When I download the jarfile, I am selecting Keep as opposed to discard the file. This is a standard mac practice to prevent malware. It seems that by copying the file to the bin stub is not a valid solution. I'm sure there are other mac users that have figured out how to use this jar file.
I am also not a java user, so I might be missing something very simple. I installed java using brew cask install java like in the documentation.
Thanks for your help.
