.add("foo : bak") // Name trailing whitespace is trimmed.
        .add("\tkey\t:\tvalue\t") // '\t' also counts as whitespace
        .add("ping:  pong  ") // Value whitespace is trimmed.
        .add("kit:kat") // Space after colon is not required.
        .build()
    assertThat(headers.values("foo")).containsExactly("bar", "baz", "bak")
    assertThat(headers.values("key")).containsExactly("value")