# File lib/aws/s3/client.rb, line 1691
        def validate_parts!(parts)
          validate!("parts", parts) do
            if !parts.kind_of?(Array)
              "must not be blank"
            elsif parts.empty?
              "must contain at least one entry"
            elsif !parts.all? { |p| p.kind_of?(Hash) }
              "must be an array of hashes"
            elsif !parts.all? { |p| p[:part_number] }
              "must contain part_number for each part"
            elsif !parts.all? { |p| p[:etag] }
              "must contain etag for each part"
            elsif parts.any? { |p| p[:part_number].to_i < 1 }
              "must not have part numbers less than 1"
            end
          end
        end