# File lib/grape_entity/options.rb, line 88
      def except_fields(for_key = nil)
        return nil unless @has_except

        @except_fields ||= @opts_hash[:except].each_with_object({}) do |attribute, allowed_fields|
          build_symbolized_hash(attribute, allowed_fields)
        end

        only_for_given(for_key, @except_fields)
      end