[Groovy/Scriptrunner Listener] To create Subtask for each group in multiselect with validation

[Joshua Procious]

Hello, I need to create a custom listener that creates a sub-task for each selection in a multi-select group picker from the parent issue. Then it needs to validate that the sub-task doesn't already exist. If it does exist, don't create the sub-task (that way if the issue is transitioned around states it doesn't create new sub-tasks.) The reason it needs to create on update is that an issue may sit at one state and have multiple groups added to review the sub-task created.

So far I've created the script runner to create the sub-task upon addition of selection from the parent issue. 

all I have for "condition" is: 

//if no selection was made do not create subtask

cfValues['Sponsoring Work Groups'] != null

and for "additional issue actions" I have:

//create the new subtask with summary set to the sponsoring workgroup for ease of //tracking. (still needs to be resolved to string instead of immutablegroup reference sigh)

def (str) = cfValues['Sponsoring Work Groups']

issue.summary = str.toString()