Iterator<Entry<String, Collection<Integer>>> iterator = multimap.asMap().entrySet().iterator();
    Entry<String, Collection<Integer>> entry = iterator.next();
    assertEquals(null, entry.getKey());
    assertThat(entry.getValue()).containsExactly(7, 3, 1);
    entry = iterator.next();
    assertEquals("tree", entry.getKey());
    assertThat(entry.getValue()).containsExactly(null, 0);

	// Initialize sync waitgroup.
	g := errgroup.WithNErrs(len(localDrives))

	// Disk states slices
	beforeState := make([]string, len(localDrives))
	afterState := make([]string, len(localDrives))

	// Make a volume entry on all underlying storage disks.
	for index := range localDrives {
		g.Go(func() (serr error) {
			if localDrives[index] == nil {
				beforeState[index] = madmin.DriveStateOffline

    @SuppressWarnings("unchecked")
    Entry<String, String>[] array = (Entry<String, String>[]) new Entry<?, ?>[entries.length];
    int i = 0;
    for (Object o : entries) {
      @SuppressWarnings("unchecked")
      Entry<String, String> e = (Entry<String, String>) o;
      array[i++] = e;
    }
    return create(array);
  }

  protected abstract Map<String, String> create(Entry<String, String>[] entries);

  @Override

    @SuppressWarnings("unchecked")
    Entry<String, String>[] array = (Entry<String, String>[]) new Entry<?, ?>[entries.length];
    int i = 0;
    for (Object o : entries) {
      @SuppressWarnings("unchecked")
      Entry<String, String> e = (Entry<String, String>) o;
      array[i++] = e;
    }
    return create(array);
  }

  protected abstract BiMap<String, String> create(Entry<String, String>[] entries);

  @Override

    @SuppressWarnings("unchecked")
    Entry<String, String>[] array = (Entry<String, String>[]) new Entry<?, ?>[entries.length];
    int i = 0;
    for (Object o : entries) {
      @SuppressWarnings("unchecked")
      Entry<String, String> e = (Entry<String, String>) o;
      array[i++] = e;
    }
    return create(array);
  }

  protected abstract BiMap<String, String> create(Entry<String, String>[] entries);

  @Override

   */
  private static <B extends @Nullable Object> Entry<Class<? extends @NonNull B>, B> checkedEntry(
      Entry<Class<? extends @NonNull B>, B> entry) {
    return new ForwardingMapEntry<Class<? extends @NonNull B>, B>() {
      @Override
      protected Entry<Class<? extends @NonNull B>, B> delegate() {
        return entry;
      }

      @Override

        // Assert
        assertNotNull(entries, "Entries array should not be null");
        assertEquals(1, entries.length, "Exactly one entry is expected");
        AppConfigurationEntry e = entries[0];
        assertNotNull(e, "Entry should not be null");
        assertEquals(EXPECTED_LOGIN_MODULE, e.getLoginModuleName(), "Login module should be Kerberos");

    }

    public static <K, T extends Map<K, Artifact>> T copyArtifacts(Map<K, ? extends Artifact> from, T to) {
        if (from != null) {
            for (Map.Entry<K, ? extends Artifact> entry : from.entrySet()) {
                to.put(entry.getKey(), ArtifactUtils.copyArtifact(entry.getValue()));
            }
        }

        return to;
    }

    private static <T> List<T> copyList(List<T> original) {

  @Override
  public Set<Entry<K, V>> create(Object... elements) {
    Entry<K, V>[] entries = createArray(elements.length);
    arraycopy(elements, 0, entries, 0, elements.length);
    return createFromEntries(entries);
  }

  public abstract Set<Entry<K, V>> createFromEntries(Entry<K, V>[] entries);

  @Override
  @SuppressWarnings("unchecked") // generic arrays make typesafety sad
  public Entry<K, V>[] createArray(int length) {

  @SafeVarargs
  public static <K, V> ImmutableMap<K, V> ofEntries(Entry<? extends K, ? extends V>... entries) {
    @SuppressWarnings("unchecked") // we will only ever read these
    Entry<K, V>[] entries2 = (Entry<K, V>[]) entries;
    return copyOf(Arrays.asList(entries2));
  }

  /**
   * Verifies that {@code key} and {@code value} are non-null, and returns a new immutable entry
   * with those values.
   *