try {
      builder.add((String) null);
      fail("expected NullPointerException"); // COV_NF_LINE
    } catch (NullPointerException expected) {
    }

    builder = this.<String>builder();
    try {
      builder.add((String[]) null);
      fail("expected NullPointerException"); // COV_NF_LINE
    } catch (NullPointerException expected) {
    }

    builder = this.<String>builder();
    try {

    try {
      builder.add((String) null);
      fail("expected NullPointerException"); // COV_NF_LINE
    } catch (NullPointerException expected) {
    }

    builder = this.<String>builder();
    try {
      builder.add((String[]) null);
      fail("expected NullPointerException"); // COV_NF_LINE
    } catch (NullPointerException expected) {
    }

    builder = this.<String>builder();
    try {

      int j = findNextJ();
      if (j == -1) {
        nextPermutation = null;
        return;
      }
      /*
       * requireNonNull is safe because we don't clear nextPermutation until we're done calling this
       * method.
       */
      requireNonNull(nextPermutation);

      int l = findNextL(j);
      Collections.swap(nextPermutation, j, l);
      int n = nextPermutation.size();

   * @see Verify#verify Verify.verify()
   */
  public static void checkState(
      boolean expression,
      /*
       * TODO(cpovirk): Consider removing @CheckForNull here, as we've done with the other methods'
       * errorMessageTemplate parameters: It is unlikely that callers intend for their string
       * template to be null (though we do handle that case gracefully at runtime). I've left this

   * {@code <A>} using our implementation unless some of its bounds have changed in resolution. This
   * avoids creating unequal TypeVariable implementation unnecessarily. When the bounds do change,
   * however, it's fine for the synthetic TypeVariable to be unequal to any native TypeVariable
   * anyway.
   */
  static final class NativeTypeVariableEquals<X> {
    static final boolean NATIVE_TYPE_VARIABLE_ONLY =

            "four", 4,
            "five", 5,
            "six", 6,
            "seven", 7,
            "eight", 8,
            "nine", 9),
        "eight",
        8,
        "five",
        5,
        "four",
        4,
        "nine",
        9,
        "one",
        1,
        "seven",
        7,
        "six",
        6,
        "three",
        3,

  static int unsafeCompare(Comparator<?> comparator, Object a, @CheckForNull Object b) {
    // Pretend the comparator can compare anything. If it turns out it can't
    // compare a and b, we should get a CCE or NPE on the subsequent line. Only methods
    // that are spec'd to throw CCE and NPE should call this.
    @SuppressWarnings({"unchecked", "nullness"})
    Comparator<@Nullable Object> unsafeComparator = (Comparator<@Nullable Object>) comparator;

          // there's a way around creating the separate sortedKeys array, and if we're allocating
          // one array of size n, we might as well allocate two -- to say nothing of the allocation
          // done in Arrays.sort.
          for (int i = 0; i < size; i++) {
            // We're careful to put only K instances in.
            if (i > 0 && comparator.compare((K) sortedKeys[i - 1], (K) sortedKeys[i]) == 0) {

    // the listener.
    executeListener(listener, executor);
  }

  /**
   * Sets the result of this {@code Future} unless this {@code Future} has already been cancelled or
   * set (including {@linkplain #setFuture set asynchronously}). When a call to this method returns,
   * the {@code Future} is guaranteed to be {@linkplain #isDone done} <b>only if</b> the call was

                doneSignal.countDown();
              }
            });
    thread.start();

    boolean done = doneSignal.await(1, TimeUnit.SECONDS);
    if (!done) {
      StringBuilder builder = new StringBuilder();
      for (StackTraceElement trace : thread.getStackTrace()) {
        builder.append("\tat ").append(trace).append('\n');
      }