assertSame(immutableList, Iterables.unmodifiableIterable((List<String>) immutableList));
  }

  public void testFrequency_multiset() {
    Multiset<String> multiset = ImmutableMultiset.of("a", "b", "a", "c", "b", "a");
    assertEquals(3, Iterables.frequency(multiset, "a"));
    assertEquals(2, Iterables.frequency(multiset, "b"));
    assertEquals(1, Iterables.frequency(multiset, "c"));

    assertSame(immutableList, Iterables.unmodifiableIterable((List<String>) immutableList));
  }

  public void testFrequency_multiset() {
    Multiset<String> multiset = ImmutableMultiset.of("a", "b", "a", "c", "b", "a");
    assertEquals(3, Iterables.frequency(multiset, "a"));
    assertEquals(2, Iterables.frequency(multiset, "b"));
    assertEquals(1, Iterables.frequency(multiset, "c"));

  public ImmutableListMultimap<String, String> parameters() {
    return parameters;
  }

  private Map<String, ImmutableMultiset<String>> parametersAsMap() {
    return Maps.transformValues(parameters.asMap(), ImmutableMultiset::copyOf);
  }

  /**
   * Returns an optional charset for the value of the charset parameter if it is specified.
   *