permitted_scalar_filter

# File actionpack/lib/action_controller/metal/strong_parameters.rb, line 537
      def permitted_scalar_filter(params, key)
        if has_key?(key) && permitted_scalar?(self[key])
          params[key] = self[key]
        end

        keys.grep(/\A#{Regexp.escape(key)}\(\d+[if]?\)\z/) do |k|
          if permitted_scalar?(self[k])
            params[k] = self[k]
          end
        end
      end