# File lib/active_model/errors.rb, line 193
    def add_on_empty(attributes, options = {})
      if options && !options.is_a?(Hash)
        options = { :message => options }
        ActiveSupport::Deprecation.warn \
          "ActiveModel::Errors#add_on_empty(attributes, custom_message) has been deprecated.\n" +
          "Instead of passing a custom_message pass an options Hash { :message => custom_message }."
      end

      [attributes].flatten.each do |attribute|
        value = @base.send(:read_attribute_for_validation, attribute)
        is_empty = value.respond_to?(:empty?) ? value.empty? : false
        add(attribute, :empty, options) if value.nil? || is_empty
      end
    end