Features used to implement the example

• Create issues and sub-tasks
  
• Assign to project role

Example: Assign new issues to a different project role depending on field value in current issue

First of all, using groups in a workflow impairs its reusability. It's much better to use project roles. You should use groups only for assigning users to project roles. As you surely know, Jira issues can only be assigned to one single user or to be unassigned.

Jira Workflow Toolbox implements a functionality for setting a default user for a project role per project. Once you have done this using project properties or user properties, you can assign your issues or sub-tasks created by Create issues and subtasks post-function as I explain in the following example.

I explain you how to assign issues according to Priority of current issue (the issue that is executing the post-function). The behavior implemented in the example is:

If Priority or current user is Critical or Blocker assign new issue to project role Managers.
If Priority or current user is Major assign new issue to project role Administrators.
Otherwise assign new issue to project role Developers.

Once configured, you have:

String expression is:

getMatchingValue(%{00017}, ["Blocker", "Critical", "Major"], ["Managers", "Managers", "Administrators", "Developers"])