multipart.addPart(
        headersOf("Content-Type", "text/plain"),
        "Hello, World!".toRequestBody(null),
      )
    }
  }

  @Test
  fun contentLengthHeaderIsForbidden() {
    val multipart = MultipartBody.Builder()
    assertFailsWith<IllegalArgumentException> {
      multipart.addPart(
        headersOf("Content-Length", "13"),
        "Hello, World!".toRequestBody(null),