Headers
        .Builder()
        .add("A", "aa")
        .add("a", "aa")
        .add("B", "bb")
        .build()
    val headers =
      Headers
        .Builder()
        .add("A", "a")
        .addAll(sourceHeaders)
        .add("C", "c")
        .build()
    assertThat(headers.toString()).isEqualTo("A: a\nA: aa\na: aa\nB: bb\nC: c\n")
  }

  @Test fun nameIndexesAreStrict() {

        NetworkBuilder.directed().allowsSelfLoops(true).build();
    mutableNetwork.addEdge("A", "A", "AA");
    mutableNetwork.addEdge("A", "B", "AB");
    Network<String, String> network = ImmutableNetwork.copyOf(mutableNetwork);

    assertThat(network.edgesConnecting("A", "A")).containsExactly("AA");
    assertThat(network.edgesConnecting("A", "B")).containsExactly("AB");

[
  {
    "comment": "Label with hyphens in 3rd and 4th position",
    "input": "aa--",
    "output": "aa--"
  },
  {
    "input": "a†--",
    "output": "xn--a---kp0a"
  },
  {
    "input": "ab--c",
    "output": "ab--c"
  },
  {
    "comment": "Label with leading hyphen",
    "input": "-x",
    "output": "-x"
  },
  {
    "input": "-†",
    "output": "xn----xhn"
  },
  {
    "input": "-x.xn--zca",

    ImmutableList<String> empty = ImmutableList.of();
    ImmutableList<String> a = ImmutableList.of("a");
    ImmutableList<String> aa = ImmutableList.of("a", "a");
    ImmutableList<String> ab = ImmutableList.of("a", "b");
    ImmutableList<String> b = ImmutableList.of("b");

    testComparator(lexy, empty, a, aa, ab, b);

    new EqualsTester()
        .addEqualityGroup(lexy, Comparators.lexicographical(comparator))