As you know we have 3 types of Authorization in WSO2 API management API Call: Basic, ApiKey, OAuth

I need to extract username of API caller. I used this way as you can see in this link: /a/78538232/7318224

<log level="custom">
  <property name="USER_NAME" expression="$ctx:api.ut.userName">
</log> 

But, This code only works if we use OAuth Authentication. So If we use Basic Authentication, this property will be NULL. Do you have any solution for that? I search the easiest way. Thank you!