Support Behaviours on sub-task issue types#103

As a ScriptRunner Admin,
I would like to set up behaviours on my sub-tasks,
So that I can apply my business rules to fields on sub-tasks

Pleaes comment with detailed use cases - they are very helpful!

My use case is to fill in the description of subtasks of different types with different text templates to preserve the identity of the filling (necessary for subsequent automation)
For example, I have a task for developers, and our workflow involves creating a subtask for a team of technical writers. I need to fill in the description of this subtask with a table with certain headers that I will use later when parsing.

I need different expert teams wroking on the same story, so I have different sub-atsk issue types for each and I nee dto have pre-defined Description field to make sure all the required info is added to the sub-task.

We used this behaviour on premise but after moving to Jira Cloud it does not work anymore :(
We want to add templates to the description field