Download ZIP using java action

Hi All,  I am trying to download multiple files into a ZIP. I have uses the following code from a java action and it just seem to keep coming up with error of contact system admin error.  that is the following code. below are screenshots of the java action and microflow. Can anyone see a clear and obvious error or does anyone have a better solution of how to get ZIP files downloaded on Mendix.  Regards, 
1 answers

What is the error message you are seeing?

Have you seen the Zip modules in the Marketplace? Using these may be easier that writing your own.