console_bulkUpdateUser_issueKeyList

import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.issue.Issue
import com.atlassian.jira.issue.IssueManager
import com.atlassian.jira.issue.CustomFieldManager
import com.atlassian.jira.issue.fields.CustomField
import com.atlassian.jira.user.ApplicationUser

// Define the issue keys you want to search for
def issueKeys = ["KEY-123", "KEY-124", "KEY-125"]
 
// change keys as needed

IssueManager issueManager = ComponentAccessor.getIssueManager()
CustomFieldManager customFieldManager = ComponentAccessor.getCustomFieldManager()
def userManager = ComponentAccessor.getUserManager()

// Replace 'CustomFieldName' with the name of your custom field
CustomField customField = customFieldManager.getCustomFieldObjectsByName("Product Owner")[0]

issueKeys.each { key ->
    Issue issue = issueManager.getIssueByCurrentKey(key)
    
    if (issue) {
        ApplicationUser user = userManager.getUserByName("john_Doe") // Replace 'caselc' with the username of the user you want to set

        if (user) {
            issue.setCustomFieldValue(customField, user)
            issueManager.updateIssue(
                ComponentAccessor.getJiraAuthenticationContext().getLoggedInUser(), 
                issue, 
                com.atlassian.jira.event.type.EventDispatchOption.DO_NOT_DISPATCH, 
                false
            )
        } else {
            println "User not found for key $key"
        }
    } else {
        println "Issue not found for key $key"
    }
}