|Content-Type: text/plain; charset=utf-8
      |Content-ID: abc
      |
      |abcd
      |efgh
      |--simple boundary
      |Content-Type: text/plain; charset=utf-8
      |Content-ID: ijk
      |
      |ijkl
      |mnop
      |
      |--simple boundary--
      """.trimMargin()
        .replace("\n", "\r\n")

    val parts =
      MultipartReader(
        boundary = "simple boundary",