def subscribes_to_optional_target?(key, optional_target_name, subscribe_as_default = ActivityNotification.config.subscribe_as_default)
      !subscription_allowed?(key) || _subscribes_to_optional_target?(key, optional_target_name, subscribe_as_default)
    end
def subscribes_to_optional_target?(key, optional_target_name, subscribe_as_default = ActivityNotification.config.subscribe_as_default)
      !subscription_allowed?(key) || _subscribes_to_optional_target?(key, optional_target_name, subscribe_as_default)
    end
Returns if the target subscribes to the specified optional target.
 It also returns true when the subscription management is not allowed for the target.

 @param [String]         key                  Key of the notification
 @param [String, Symbol] optional_target_name Class name of the optional target implementation (e.g. :amazon_sns, :slack)
 @param [Boolean]        subscribe_as_default Default subscription value to use when the subscription record does not configured
 @return [Boolean] If the target subscribes the notification email or the subscription management is not allowed for the target