Hi Mike,
I know this is possible because the setParameter() method for the GlobalContainer takes an Object type for the second parameter meaning that you can put any Java Object as the value. I have actually done this same sort of thing with the GlobalContainer for one of my requirements to read email addresses of employees on some HR interfaces. The only difference is that I did it using a Function Library similar to the post I highlighted before. Can you share the local UDF code where you have constructed and inserted the HashMap into the GlobalContainer?
Regards,
Ryan Crosby