def authenticate_with_mandrill_keys!(*keys)
      @mandrill_webhook_keys ||= []
      if keys.present?
        if keys.compact.present?
          @mandrill_webhook_keys.concat(keys.flatten)
        else
          @mandrill_webhook_keys = []
        end
      end
      @mandrill_webhook_keys
    end
def authenticate_with_mandrill_keys!(*keys)
      @mandrill_webhook_keys ||= []
      if keys.present?
        if keys.compact.present?
          @mandrill_webhook_keys.concat(keys.flatten)
        else
          @mandrill_webhook_keys = []
        end
      end
      @mandrill_webhook_keys
    end
Gets/sets the current Mandrill WebHook Authentication key(s).
 Returns the current WebHook key(s) as an Array if called with no parameters.
 If called with parameters, add the params to the WebHook key array.
 If called with nil as the parameters, clears the WebHook key array.