}

  public void testIsPresent_no() {
    assertFalse(Optional.absent().isPresent());
  }

  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
  public void testIsPresent_yes() {
    assertTrue(Optional.of("training").isPresent());
  }

  public void testGet_absent() {
    Optional<String> optional = Optional.absent();
    try {
      optional.get();
      fail();

  }

  public void testIsPresent_no() {
    assertFalse(Optional.absent().isPresent());
  }

  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
  public void testIsPresent_yes() {
    assertTrue(Optional.of("training").isPresent());
  }

  public void testGet_absent() {
    Optional<String> optional = Optional.absent();
    try {
      optional.get();
      fail();

  }

  public void test_contains_null_set_yes() {
    Iterable<@Nullable String> set = Sets.newHashSet("a", null, "b");
    assertTrue(Iterables.contains(set, null));
  }

  public void test_contains_null_set_no() {
    Iterable<String> set = Sets.newHashSet("a", "b");
    assertFalse(Iterables.contains(set, null));
  }

  public void test_contains_null_iterable_yes() {

  }

  public void test_contains_null_set_yes() {
    Iterable<@Nullable String> set = Sets.newHashSet("a", null, "b");
    assertTrue(Iterables.contains(set, null));
  }

  public void test_contains_null_set_no() {
    Iterable<String> set = Sets.newHashSet("a", "b");
    assertFalse(Iterables.contains(set, null));
  }

  public void test_contains_null_iterable_yes() {

        Class<?> theClass = Class.forName(UNSAFE_COMPARATOR_NAME);

        // requireNonNull is safe because the class is an enum.
        Object[] constants = requireNonNull(theClass.getEnumConstants());

        // yes, UnsafeComparator does implement Comparator<byte[]>
        @SuppressWarnings("unchecked")
        Comparator<byte[]> comparator = (Comparator<byte[]>) constants[0];
        return comparator;

          @Override
          public void oneDeclared() throws SomeCheckedException {
            try {
              methodThatDoesntThrowAnything();
            } catch (Throwable t) {
              // yes, this block is never reached, but for purposes of illustration
              // we're keeping it the same in each test
              Throwables.propagateIfPossible(t, SomeCheckedException.class);

          @Override
          public void oneDeclared() throws SomeCheckedException {
            try {
              methodThatDoesntThrowAnything();
            } catch (Throwable t) {
              // yes, this block is never reached, but for purposes of illustration
              // we're keeping it the same in each test
              Throwables.propagateIfPossible(t, SomeCheckedException.class);

         *
         * - in `run`, which can't run until this Runnable is submitted to an executor, which
         *   doesn't happen until below. (And this Executor -- yes, the object is both a Runnable
         *   and an Executor -- is used for only a single `execute` call.)
         */
        ThreadConfinedTaskQueue submittingTaskQueue = requireNonNull(sequencer).latestTaskQueue;

     * wrapper around j.u.HashSet, which has built-in flooding protection. MAX_RUN_MULTIPLIER was
     * determined experimentally to match our desired probability of false positives.
     */
    // NB: yes, this is surprisingly high, but that's what the experiments said was necessary
    // Raising this number slows the worst-case contains behavior, speeds up hashFloodingDetected,
    // and reduces the false-positive probability.

 * <p>"IPv4 mapped" addresses were originally a representation of IPv4 addresses for use on an IPv6
 * socket that could receive both IPv4 and IPv6 connections (by disabling the {@code IPV6_V6ONLY}
 * socket option on an IPv6 socket). Yes, it's confusing. Nevertheless, these "mapped" addresses
 * were never supposed to be seen on the wire. That assumption was dropped, some say mistakenly, in
 * later RFCs with the apparent aim of making IPv4-to-IPv6 transition simpler.