[Behavior] Set Current User to Single User Picker Custom Field on Customer Portal

[Abdulkarim Itani]

I tried the following code and the form is not updating

The behavior is mapped to the correct project (Jira Service Desk)

import com.atlassian.jira.component.ComponentAccessor
def affectedUser = getFieldByName("<You custom field name here>")

def currentuser = ComponentAccessor.jiraAuthenticationContext.loggedInUser.username

affectedUser.setFormValue(currentuser)
affectedUser.setHelpText(currentuser)

This code is updating the help text but not updating the form value.  

Am I doing anything wrong?