@Test
  fun headerAcceptsPermittedCharacters() {
    val builder = Request.Builder()
    builder.header("AZab09~", "AZab09 ~")
    builder.addHeader("AZab09~", "AZab09 ~")
  }

  @Test
  fun emptyNameForbidden() {
    val builder = Request.Builder()
    assertFailsWith<IllegalArgumentException> {
      builder.header("", "Value")
    }
    assertFailsWith<IllegalArgumentException> {