Script listener script for priorities change

[Sharadkumar Bangera]

Hello,

I am looking for Listener custom Script for my query whenever the Priorities change the Comment to be added in Jira "Priorities changed from Major to Minor".I am not good in scripting.

I m writing script listener- Fires an event when condition is true but  endup with error.

Selected Project : All Project

Event : Prioriy changed

Name of the event to fire : Priority changed

This is my script 
import groovy.xml.MarkupBuilder
import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.model.ChangeGroup
import com.atlassian.jira.model.ChangeItem
import com.atlassian.jira.issue.history.ChangeItemBean

def commentManager = ComponentAccessor.getCommentManager()
def customFieldManager = ComponentAccessor.getCustomFieldManager()
def priorityChange = changelog?.items.find { it['field'] == 'priority' }
def issue = event.issue
def user = ComponentAccessor.getJiraAuthenticationContext().getLoggedInUser()
if (!priorityChange) {
logger.info("Priority was not updated")
return
}
logger.info("Priority changed from {} to {}", priorityChange.fromString, priorityChange.toString)

Error i received

The script could not be compiled:

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
Script387.groovy: 17: unexpected char: 0xFFFF @ line 17, column 102.
   , priorityChange.toString)    
                                 ^

1 error

.