setFieldValue(String <field_name>or<field_Id>, Object value)
setFieldValue(String <field_name>or<field_Id>, Object value) method sets the value of a system or custom field of the Issue object where, 
<field_name> is the name of the field as displayed in the Field configuration<field_id>is the ID of the field as shown in Accessing the Jira Standard fields of an issue document. In the case of a custom field, it has the formcustomfield_xxxxx, wherexxxxxis the custom field numerical ID, as seen in the URL when viewing or editing the field.Object value, is the value which is same as what is expected to be returned as the result of a Groovy expression
You can use this method on any Issue object, such as the one provided by the issue, linkedIssue and parentIssue variables, as well as the Issue objects returned by other methods such as getParentObject(), getEpic() or getLinkedIssues().
Method availability:
This method is allowed only in scripts run from the
- Groovy script tester admin page: When you call this method on any Issue object passing the
<field_name>or<field_id>andObject value, inGroovy scriptof the Groovy script tester page and test it, the specified field gets set to the specified value. This is useful when you want to just set a field value without the need to trigger any transition or add a post-function.- Example: Set the Fix Version/s of the parent to the child
- Go to the JMWE administration pages
 - Click on Groovy script tester
 Write the following script in
Groovy scriptparentIssue.setFieldValue("Fix Version/s",issue.get("fixVersions"))Click on
Test Groovy scriptfrom the toolbar- Select the child 
Issue keyon whose parent you wish to set the value - Click on
Test - Go to the parent issue
 
 
 - Example: Set the Fix Version/s of the parent to the child
 
The Fix Version/s will be set to that of the child.
- Scripted (Groovy) operation on issue post-function: When you call this method on any Issue object passing the 
<field_name>or<field_id>andObject value, inGroovy scriptof Scripted (Groovy) operation on issue post-function and trigger the transition on an Epic, the specified field gets set to the specified value.- Example: Add all the Reporters of the stories as the Watchers of the Epic
- Add the post-function to a transition
 Write the following script in
Groovy scriptSet users = [] issue.stories.each{ users += it.get("reporter") } users += issue.get("watches") issue.setFieldValue("watches",users)Publish the workflow
- Trigger the transition on the Epic
 
 - Example: Set the description of the issue with the summary and issue key
- Add the post-function to a transition
 Write the following script in
Groovy scriptissue.setFieldValue("description","Create a document for the fix : ${issue.key} - ${issue.summary}")Publish the workflow
- Trigger the transition on the issue
 
 
 - Example: Add all the Reporters of the stories as the Watchers of the Epic
 
, multiple selections available,