Create Sub-tasks when a Work Item is Created

def eventWorkItem = Issues.getByKey(issue.key as String)

if (eventWorkItem.issueType.subtask) { // If the newly created work item is a subtask, skip the execution
    return
}

def listOfSummaries = ['Subtask summary 1', 'Subtask summary 2'] // The summaries to use for
def subtaskWorkItemType = 'Sub-task' // The Sub Task Work Item Type to Use

def spaceKey = eventWorkItem.getProjectObject().key

listOfSummaries.forEach { summary ->
    eventWorkItem.createSubTask(subtaskWorkItemType) {
        setSummary(summary)
    }
}