* not in {@link #nextElements}, this method throws an {@link UnknownElementException}.
     *
     * <p>This method is used when testing iterators without a known ordering. We poll the target
     * iterator's next element and pass it to the reference iterator through this method so it can
     * return the same element. This enables the assertion to pass and the reference iterator to

  };

  static final Supplier<TreeSet<String>> STRING_TREESET_FACTORY =
      new Supplier<TreeSet<String>>() {
        @Override
        public TreeSet<String> get() {
          return new TreeSet<>(Ordering.natural().nullsLast());
        }
      };

  static void populateMultimapForGet(Multimap<Integer, String> multimap, String[] elements) {
    multimap.put(2, "foo");
    for (String element : elements) {

  }

  /**
   * This test will fail whenever someone updates/reorders the BloomFilterStrategies constants. Only
   * appending a new constant is allowed.
   */
  // This test ensures that our reliance on the ordering elsewhere is safe.
  @SuppressWarnings("EnumOrdinal")
  public void testBloomFilterStrategies() {
    assertThat(BloomFilterStrategies.values()).hasLength(2);

        checkInvalidRange("[1.0,1.2),1.3");
        // overlap
        checkInvalidRange("[1.0,1.2),(1.1,1.3]");
        // overlap
        checkInvalidRange("[1.1,1.3),(1.0,1.2]");
        // ordering
        checkInvalidRange("(1.1,1.2],[1.0,1.1)");
    }

    @Test
    @SuppressWarnings("checkstyle:MethodLength")
    void testIntersections() throws InvalidVersionSpecificationException {

        // </mirrors>

        for (Mirror mirror : settings.getMirrors()) {
            request.addMirror(new org.apache.maven.settings.Mirror(mirror));
        }

        // Collect repositories; are sensitive to ordering
        LinkedHashMap<String, Repository> remoteRepositories = new LinkedHashMap<>();
        LinkedHashMap<String, Repository> remotePluginRepositories = new LinkedHashMap<>();

        // settings/repositories

     *
     * @param <E> the element type of {@link PriorityBlockingQueue}
     * @param initialCapacity the initial capacity of the priority queue
     * @param comparator the comparator for ordering the elements in the priority queue
     * @return a new instance of {@link PriorityBlockingQueue}
     * @see PriorityBlockingQueue#PriorityBlockingQueue(int, Comparator)
     */

  /**
   * Returns a comparator that compares two {@code char} arrays <a
   * href="http://en.wikipedia.org/wiki/Lexicographical_order">lexicographically</a>; not advisable
   * for sorting user-visible strings as the ordering may not match the conventions of the user's
   * locale. That is, it compares, using {@link #compare(char, char)}), the first pair of values

   * computation is {@linkplain java.util.concurrent.Future#isDone() complete} or, if the
   * computation is already complete, immediately.
   *
   * <p>The callback is run on {@code executor}. There is no guaranteed ordering of execution of
   * callbacks, but any callback added through this method is guaranteed to be called once the
   * computation is complete.
   *
   * <p>Example:
   *
   * {@snippet :
   * future.addCallback(

    ImmutableListMultimap.Builder<String, Integer> builder = ImmutableListMultimap.builder();
    builder.put("bb", 3);
    builder.put("d", 2);
    builder.put("a", 5);
    builder.orderKeysBy(
        new Ordering<String>() {
          @Override
          public int compare(String left, String right) {
            return left.length() - right.length();
          }
        });
    builder.put("cc", 4);

   */
  private static final class ThreadConfinedTaskQueue {
    /**
     * This field is only used for identity comparisons with the current thread. Field assignments
     * are atomic, but do not provide happens-before ordering; however:
     *
     * <ul>
     *   <li>If this field's value == currentThread, we know that it's up to date, because write
     *       operations in a thread always happen-before subsequent read operations in the same