There is no need to do that. If you configure the scheduled task as we suggested, it will never do anything for accounts with empty custom attributes. Moreover, the task clears them in the end.
I think you misunderstand. As it sits right now, I have several users that has data in ExtensionAttribute1 in Exchange Online. If I run the schedule task as described, the blank adm-CustomAttributeText1 will CLEAR ExtensionAttribute1 because adm-CustomAttributeText1 is blank.
Here's an example:
Here is the Scheduled Task
Here is a user with data in ExchangeOnline in their CustomAttribute4 and CustomAttribute5 fields;
but NOTHING in adm-CustomAttributeText4 and adm-CustomAttributeText5
Now when I run the scheduled task against this user, those fields clear out
These clear out because the Logic is checking ExtensionAttribute4 and ExtensionAttribute5 which according to Adaxes, is empty
You can see the Test User's CustomAttribute4 is now Empty in Exchange
I need Adaxes to either properly populate ExtensionAttribute from Exchange or a way to back-fill all adm-CustomAttributeText with existing values from ExtensionAttribute