Hi Guys,
Need one help in Updating Fix Version of the Linked Issue. Issue Link type = "Covers".
I have tried to write a code, but it 's not working throwing an error. Please help me getting this fixed. 

import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.issue.ModifiedValue
import com.atlassian.jira.issue.util.DefaultIssueChangeHolder
import com.atlassian.jira.issue.link.IssueLink
import com.atlassian.jira.issue.link.IssueLinkManager
import java.time.LocalDateTime
import java.time.format.DateTimeFormatter
final customFieldName = 'Fix Version/s'
Issue fix_Issue = event.getIssue()
if (fix_Issue.issueTypeObject.name == "Story" )
{
List changeItems = event.getChangeLog().getRelated("ChildChangeItem")
if( fix_Issue.fixVersions?.name && changeItems.any {it.get('field')=='Fix Version'} )
{
Collection<Version> fixVersions = new ArrayList<Version>();
fixVersions = fix_Issue.getFixVersions()
}
def linkedIssues = ComponentAccessor.issueLinkManager
.getOutwardLinks(issue.id)
.findAll { it.issueLinkType.name in ['Covers'] && it.destinationObject.issueType.name == "Story" }
if (!linkedIssues) {
return
}
def customField = ComponentAccessor.customFieldManager.getCustomFieldObjects(issue)?.find {
it.name == customFieldName
}
linkedIssues.each {
def linkedIssue = it.destinationObject
def newValue = fixVersions
customField.updateValue(null, linkedIssue, new ModifiedValue(newValue), new DefaultIssueChangeHolder())
}