}.also { expected ->
      assertThat(expected.message)
        .isEqualTo("Unexpected char 0xe9 at 1 in header name: héader1")
    }
  }

  @Test fun builderRejectsUnicodeInHeaderValue() {
    assertFailsWith<IllegalArgumentException> {
      Headers.Builder().add("header1", "valué1")
    }.also { expected ->
      assertThat(expected.message)