Grails Audit Logging: Selective auditing and onChange method

Question

We are using grails audit logging plugin for auditing few domain objects in our project https://grails.org/plugin/audit-logging

Facing couple of issues related to it:

1. We have a user domain object which we want to audit. We also create lot of users during our system set up. So, when we make auditable = true for User domain, it audits that as well - creates a new row in audit_log_event table for each user that gets created.

   Is there a way to avoid this? We just want to audit when a user is created/updated by an admin user (basically when the admin user is logged in)

2. For some of the attributes of a domain object that we are auditing, we want to make some modification in the new value. Example: Lets say email address of User object is getting updated from a@gmail.com to b@gmail.com, then we want to insert "***B@gmail.com-12:23:47" in new_value column of audit_log_event table.

   I thought by updating the value of newMap[key] in onChange() method, we can do this, but that doesn't seem to work. Is there a way to do this?

   Tried this:

def onChange = {
           oldMap,newMap ->
              println "User was changed ..."

              oldMap.each({ key, oldVal ->
                 if(oldVal != newMap[key]) {
                    println " * $key changed from $oldVal to " + newMap[key]

                    if(key == "email") {
                        newMap[key] = "*****Some value udpated****"
                        println "email is now again changed ..."
                        println " * $key changed from $oldVal to " + newMap[key]
                    }
                 }
              })
}

Console output:

   User was changed ...
    * email changed from a@gmail.com to b@gmail.com
   email is now again changed ...
    * email changed from a@gmail.com to *****Some value udpated****

However, in DB:

old_value = a@gmail.com
new_value = b@gmail.com