Default custom field values not set in sub-task created by Create Sub-task post-function

In JIRA you have the ability to automatically set default values for your custom fields via the custom field configuration page. However, if you set a custom field to have default values, they will not be set when creating a sub-task via the ScriptRunner Create Sub-task post-function as you would expect.

Steps to reproduce:

• Create a new custom checkbox field and give it some random options.
• Then configure that checkbox field to only appear on sub-tasks and set the default value of the field:

• Now configure a Create Subtask post-function that executes on a transition of your choice.
  • Remember to publish the workflow before exiting
• Create a new issue for testing
• On your newly created issue, click the "More" tab and open the dialog to manually create a subtask. Notice that the values for your custom field are set to the defaults as you would expect.
• Exit that dialog without creating a sub-task and then execute the transition that you attached the Create Sub-task post-function to.
• Notice in the newly created subtask that the default values were not set!

Workaround

In the additional issue actions field, include the following script

import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.issue.context.IssueContextImpl

def issueContext = new IssueContextImpl(issue.projectId, issue.issueTypeId)

def cf = ComponentAccessor.customFieldManager.getCustomFieldObjectByName("CustomFieldName")
def fieldConfig = ComponentAccessor.fieldConfigSchemeManager.getRelevantConfig(issueContext, cf)
def defaultValue = cf.getCustomFieldType().getDefaultValue(fieldConfig)

issue.setCustomFieldValue(cf, defaultValue)