23a60e63__Core_API___endpoint_reference__description
[field] modifier [description] 
For files within a shared folder, this field specifies which user last modified this file. The value is a user dictionary with the fields uid (user ID), display_name, and, if the linked account is a member of a Dropbox for Business team, same_team (whether the user is on the same team as the linked account). If this endpoint is called by a Dropbox for Business app and the user is on that team, a member_id field will also be present in the user dictionary. If the modifying user no longer exists, the value will be null.
Dropbox - Core API - endpoint reference
description