private static final SparseImmutableTable<Character, Integer, String> SPARSE =
      new SparseImmutableTable<>(CELLS.asList(), ROW_SPACE, COLUMN_SPACE);

  private static final DenseImmutableTable<Character, Integer, String> DENSE =
      new DenseImmutableTable<>(CELLS.asList(), ROW_SPACE, COLUMN_SPACE);

  @Override
  Iterable<ImmutableTable<Character, Integer, String>> getTestInstances() {

/**
 * Represents an alternate link entry within a sitemap URL.
 * This class encapsulates the properties of an alternate link as defined in the hreflang annotation.
 *
 * <p>
 * The hreflang attribute tells search engines about alternate versions of a page in different languages
 * or for different regions. This helps search engines serve the correct language or regional URL
 * to searchers.
 * </p>
 *

    // tells the computing thread when to start computing
    CountDownLatch computeSignal = new CountDownLatch(1);
    // tells the main thread when computation is pending
    CountDownLatch secondSignal = new CountDownLatch(1);
    // tells the main thread when the second get has started
    CountDownLatch thirdSignal = new CountDownLatch(1);
    // tells the main thread when the third get has started

    // tells the computing thread when to start computing
    CountDownLatch computeSignal = new CountDownLatch(1);
    // tells the main thread when computation is pending
    CountDownLatch secondSignal = new CountDownLatch(1);
    // tells the main thread when the second get has started
    CountDownLatch thirdSignal = new CountDownLatch(1);
    // tells the main thread when the third get has started

 *   }
 * }
 *
 * public void testMySubtypes() throws Exception {
 *   new MySubtypeTests().testAllDeclarations();
 * }
 * }
 *
 * The calls to {@link #isSubtype} and {@link #notSubtype} tells the framework what assertions need
 * to be made.
 *
 * <p>The declaration methods must be public.
 */
@AndroidIncompatible // only used by android incompatible tests.
@NullUnmarked

 *   }
 * }
 *
 * public void testMySubtypes() throws Exception {
 *   new MySubtypeTests().testAllDeclarations();
 * }
 * }
 *
 * The calls to {@link #isSubtype} and {@link #notSubtype} tells the framework what assertions need
 * to be made.
 *
 * <p>The declaration methods must be public.
 */
@AndroidIncompatible // only used by android incompatible tests.
@NullUnmarked

          }
        };

    recursiveCache = CacheBuilder.newBuilder().weakKeys().weakValues().build(recursiveLoader);
    cacheRef.set(recursiveCache);

    // tells the test when the computation has completed
    CountDownLatch doneSignal = new CountDownLatch(1);

    Thread thread =
        new Thread() {
          @Override
          public void run() {
            try {

   *
   * <p>The returned set's iterator traverses the mappings with the first row key, the mappings with
   * the second row key, and so on.
   *
   * <p>The value in the returned cells may change if the table subsequently changes.
   *
   * @return set of table cells consisting of row key / column key / value triplets
   */
  @Override
  public Set<Cell<R, C, @Nullable V>> cellSet() {
    return super.cellSet();
  }

  @Override