Update Parent With Estimate Sum

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

def parent = eventIssue.parentObject
def subtasks = parent.subtasks
logger.info("Total subtasks for ${parent.key}: ${subtasks.size()}")

// Sum the estimates
def estimate = subtasks.sum { subtask ->
    subtask.getCustomFieldValue('Time Estimate') ?: 0
}
logger.info("Summed estimate: ${estimate}")

parent.update {
    setCustomFieldValue('Summed Subtask Estimate', estimate)
}