Groovy Script NPE error when updating multi-user custom field in a post function

[Atlassian Admin _Zynga_]

I have the below script to update a multi-user custom field in a post function.

import com.atlassian.jira.user.ApplicationUsers

import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.user.ApplicationUser
import com.atlassian.jira.issue.MutableIssue
import com.atlassian.jira.issue.fields.CustomField
import com.atlassian.jira.issue.IssueManager
import com.atlassian.jira.issue.ModifiedValue
import com.atlassian.jira.issue.util.IssueChangeHolder;
import com.atlassian.jira.issue.fields.layout.field.FieldLayoutItem;
import com.atlassian.jira.issue.util.DefaultIssueChangeHolder;
import com.atlassian.jira.event.type.EventDispatchOption
import com.atlassian.jira.issue.Issue

IssueManager issueManager = ComponentAccessor.getIssueManager();
MutableIssue issue = issueManager.getIssueObject(issue.id);
def subTasks = issue.getSubTaskObjects()
List<ApplicationUser> users;
CustomField multiUser = ComponentAccessor.getCustomFieldManager().getCustomFieldObjectByName("CC List")

subTasks.each {
String assignee1 = it.assigneeId
if(users == null)
users = new ArrayList<>();
users.add(ComponentAccessor.getUserManager().getUserByName(assignee1))
}

issue.setCustomFieldValue(multiUser, users);
issueManager.updateIssue(ComponentAccessor.getJiraAuthenticationContext().getLoggedInUser(), issue, EventDispatchOption.ISSUE_UPDATED, false)

The field gets updated in the issue after adding the last line, but also seeing the below error in the logs.

2019-02-09 13:43:59,780 ERROR [workflow.ScriptWorkflowFunction]: *************************************************************************************
2019-02-09 13:43:59,781 ERROR [workflow.ScriptWorkflowFunction]: Script function failed on issue: FA-635, actionId: 51, file: <inline script>
java.lang.NullPointerException
	at com.atlassian.jira.issue.customfields.impl.MultiUserCFType.getChangelogValue(MultiUserCFType.java:123)
	at com.atlassian.jira.issue.customfields.impl.MultiUserCFType.getChangelogValue(MultiUserCFType.java:80)
	at com.atlassian.jira.issue.fields.ImmutableCustomField.getChangelogValue(ImmutableCustomField.java:376)
	at com.atlassian.jira.issue.fields.ImmutableCustomField.updateValue(ImmutableCustomField.java:411)
	at com.atlassian.jira.issue.fields.ImmutableCustomField.updateValue(ImmutableCustomField.java:396)
	at com.atlassian.jira.issue.managers.DefaultIssueManager.updateFieldValues(DefaultIssueManager.java:704)
	at com.atlassian.jira.issue.managers.DefaultIssueManager.updateIssue(DefaultIssueManager.java:669)
	at com.atlassian.jira.issue.managers.DefaultIssueManager.updateIssue(DefaultIssueManager.java:655)
	at com.atlassian.jira.issue.managers.RequestCachingIssueManager.updateIssue(RequestCachingIssueManager.java:214)
	at com.atlassian.jira.issue.IssueManager$updateIssue$2.call(Unknown Source)
	at Script350.run(Script350.groovy:32)

Could someone help resolve the issue?

[Alejandro Suárez - TecnoFor · Accepted solution]

Hi @Atlassian Admin _Zynga_ ,

You could use something like this:

import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.event.type.EventDispatchOption
import com.atlassian.jira.issue.CustomFieldManager
import com.atlassian.jira.issue.IssueManager
import com.atlassian.jira.issue.fields.CustomField
import com.atlassian.jira.user.ApplicationUser

IssueManager issueManager = ComponentAccessor.getIssueManager()
CustomFieldManager customFieldManager = ComponentAccessor.getCustomFieldManager()
ApplicationUser currentUser = ComponentAccessor.getJiraAuthenticationContext().getLoggedInUser()

CustomField multiUser = customFieldManager.getCustomFieldObjectByName("CC List")
ArrayList<ApplicationUser> users = []

issue.getSubTaskObjects()?.each {
    if (it.getAssignee()) users.add(it.getAssignee())
}

if (users) {
    issue.setCustomFieldValue(multiUser, users)
    issueManager.updateIssue(currentUser, issue, EventDispatchOption.ISSUE_UPDATED, false)
}

[Atlassian Admin _Zynga_]

Thanks @Alejandro Suárez - TecnoFor . This script worked fine without any errors. Could you please clarify on the issue with the original script?

[Alejandro Suárez - TecnoFor]

Sure, the initial problem with your code is that you are getting those exceptions because in some subtasks the assignee field is null. You have to check that field if you dont want to log null exceptions. 

And you complex more than necesary your code, for example, you are cheking if the users variable is null when it allways will be null, and you are using a method from userManager to get an ApplicationUser, when issue.getAssignee() method gives you an ApplicationUser itself.

Regards

[Atlassian Admin _Zynga_]

Thanks for the clarification @Alejandro Suárez - TecnoFor