code: def update_delegate(owner, delegate, permissions)
        action = "#{SOAP_ACTION_PREFIX}/UpdateDelegate"
        resp = invoke("#{NS_EWS_MESSAGES}:UpdateDelegate", action) do |root|
          build!(root) do
            add_delegate!(owner, delegate, permissions)
          end
        end
        parse_soap_response(resp)
      end
docs: Updates delegate permissions on a principal's mailbox
   @see http://msdn.microsoft.com/en-us/library/bb856529.aspx
  
   @param [String] owner The user that is delegating permissions
   @param [String] delegate The user that is being given delegate permission
   @param [Hash] permissions A hash of permissions that will be delegated.
     This Hash will eventually be passed to add_hierarchy! in the builder so it is in that format.