I have REST API url: http://siteURL.com/_api/SP.UserProfiles.PeopleManager/GetUserProfilePropertyFor(accountName=@v,propertyName='Manager')?@v='[%Variable:user%]'
It works for me for propertyName = Manager I need to get other field through similar REST API call named "extensionAttribute1" which is Exchange atribute in Active Directory. I tried to change "Manager" to "extensionAttribute1" in URL above, but it gives me no value.
I work with SharePoint Online.
Could you help me, please?