instance method values_for_create

# File activerecord/lib/active_record/relation.rb, line 616
      def values_for_create(attributes = nil)
        result = attributes ? where_values_hash.merge!(attributes) : where_values_hash

        # NOTE: if there are same keys in both create_with and result, create_with should be used.
        # This is to make sure nested attributes don't get passed to the klass.new,
        # while keeping the precedence of the duplicate keys in create_with.
        create_with_value.stringify_keys.each do |k, v|
          result[k] = v if result.key?(k)
        end

        result
      end