/*
 * All right, title and interest in this code snippet shall remain the exclusive intellectual property of Adaptavist Group Ltd and its affiliates. Customers with a valid ScriptRunner
 * license shall be granted a  non-exclusive, non-transferable, freely revocable right to use this code snippet only within their own instance of Atlassian products. This licensing notice cannot be removed
 * or amended and must be included in any circumstances where the code snippet is shared by You or a third party."
 */
 
import com.adaptavist.hapi.jira.issues.Issues
import com.atlassian.jira.user.ApplicationUser

def projectKey = '<ENTER_THE_PROJECT_KEY>'
def sourceFieldName = '<ENTER_THE_FIELD_NAME>'
def destinationFieldName = '<ENTER_THE_FIELD_NAME>'


Issues.search("""project = ${projectKey} and "${sourceFieldName}"  is not EMPTY""").each {
    def issue = it
    def users = issue.getCustomFieldValue(sourceFieldName) as List<ApplicationUser>

    def selectedUsers = users.collect {
        it.username
    }.toString()

    def updated = selectedUsers.replace('[','').replace(']','').trim()

    issue.update {
        setCustomFieldValue(destinationFieldName, updated)
    }
}