}

  public void testExecutors_nullCheck() throws Exception {
    new ClassSanityTester()
        .setDefault(RateLimiter.class, RateLimiter.create(1.0))
        .forAllPublicStaticMethods(MoreExecutors.class)
        .thatReturn(Executor.class)
        .testNulls();
  }

  private static class TestApplication extends Application {
    private final List<Thread> hooks = new ArrayList<>();

 * public class Books {
 *   public static Book hardcover(String title) {...}
 *   public static Book paperback(String title) {...}
 * }
 * </pre>
 *
 * <p>please use {@link ClassSanityTester#forAllPublicStaticMethods}.
 *
 * <p>If not all classes on the classpath should be covered, {@link #ignoreClasses} can be used to
 * exclude certain classes. As a special case, classes with an underscore in the name (like {@code

  }

  public void testExecutors_nullCheck() throws Exception {
    new ClassSanityTester()
        .setDefault(RateLimiter.class, RateLimiter.create(1.0))
        .forAllPublicStaticMethods(MoreExecutors.class)
        .thatReturn(Executor.class)
        .testNulls();
  }

  private static class TestApplication extends Application {
    private final List<Thread> hooks = new ArrayList<>();

  }

  @J2ktIncompatible
  @GwtIncompatible // reflection
  public void testIterables_nullCheck() throws Exception {
    new ClassSanityTester()
        .forAllPublicStaticMethods(Iterables.class)
        .thatReturn(Iterable.class)
        .testNulls();
  }

  private static void verifyMergeSorted(