How to clear assignee using script runner custom listener

[Srikanth Kola]

I need to clear assignee field in JIRA using script runner custom listener. 

I wrote the below script to listen to field "Assigned Workgroup" when it is updated then I want to clear Assignee field

import com.atlassian.jira.ComponentManager
import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.issue.MutableIssue
import java.sql.Timestamp
import groovy.time.TimeCategory
import java.time.*

def issue = event.getIssue()
def issueKey = issue.getKey()
def issueInputParameters = issue.getAssignee()
def date1 = new Timestamp(new Date().getTime())
def date2 = new Timestamp(new Date().getTime() - 5000)

def changeHistoryManager = ComponentAccessor.getChangeHistoryManager()
def change = changeHistoryManager.getChangeItemsForField(issue, "Assigned Workgroup")
String KISH = change.findAll{it.created < date1 && it.created > date2}

if (KISH == '[]'){
return null
}else{
issue.setAssignee(null)  - This line throws error saying "check if declared type is right and if the method exists"
}

[Alexey Matveev · Accepted solution]

Try to run the script. I think it is just a static compilation error. If you run it, then it should work

[Srikanth Kola]

Yes it did, the error was misleading. Thank you

[Kumar]

HI @Srikanth Kola @Alexey Matveev 

I have same requirement When ever the Group Picker field is changed or updated or Empty

Then make assignee field as EMPTY (Unassigned) on issue

So i used the above script in the script listener so issue update even for me its not working 

can you please help me how to make it work 

Thanks,

Kumar