return false;
    }

    Object target = thatIterator.next();
    E current = thisIterator.next();
    try {
      while (true) {
        int cmp = unsafeCompare(current, target);

        if (cmp < 0) {
          if (!thisIterator.hasNext()) {
            return false;
          }
          current = thisIterator.next();
        } else if (cmp == 0) {
          if (!thatIterator.hasNext()) {

    }

    /**
     * Checks if a next page exists.
     *
     * @return true if a next page exists, false otherwise
     */
    public boolean isExistNextPage() {
        return existNextPage;
    }

    /**
     * Sets whether a next page exists.
     *
     * @param existNextPage true if a next page exists
     */

        assertThat(it.hasNext(), is(true));
        assertThat(it.next(), is(sameInstance(cl3)));

        assertThat(it.hasNext(), is(true));
        assertThat(it.next(), is(sameInstance(cl2)));

        assertThat(it.hasNext(), is(true));
        assertThat(it.next(), is(sameInstance(cl1)));

        assertThat(it.hasNext(), is(not(true)));
    }

    Iterator<Entry<E>> entryIterator = entryIterator();
    return entryIterator.hasNext() ? entryIterator.next() : null;
  }

  @Override
  public @Nullable Entry<E> lastEntry() {
    Iterator<Entry<E>> entryIterator = descendingEntryIterator();
    return entryIterator.hasNext() ? entryIterator.next() : null;
  }

  @Override
  public @Nullable Entry<E> pollFirstEntry() {

    assertThrows(
        ConcurrentModificationException.class,
        () -> {
          Iterator<Entry<K, V>> iterator = getMap().entrySet().iterator();
          getMap().clear();
          iterator.next();
        });
  }

  @MapFeature.Require({FAILS_FAST_ON_CONCURRENT_MODIFICATION, SUPPORTS_REMOVE})
  @CollectionSize.Require(SEVERAL)
  public void testClearConcurrentWithKeySetIteration() {
    assertThrows(

   */
  protected @Nullable Entry<E> standardFirstEntry() {
    Iterator<Entry<E>> entryIterator = entrySet().iterator();
    if (!entryIterator.hasNext()) {
      return null;
    }
    Entry<E> entry = entryIterator.next();
    return Multisets.immutableEntry(entry.getElement(), entry.getCount());
  }

  @Override
  public @Nullable Entry<E> lastEntry() {
    return delegate().lastEntry();
  }

  /**

       * initialized by next() -- which initializes rowEntry, too.
       *
       * - rowEntry isn't cleared except below. If it was cleared below, then either
       *   columnIterator.remove() would have failed above (if the user hasn't called next() since
       *   then) or rowEntry would have been initialized by next() (as discussed above).
       */

  @Override
  public final boolean hasNext() {
    return backingIterator.hasNext();
  }

  @Override
  @ParametricNullness
  public final T next() {
    return transform(backingIterator.next());
  }

  @Override
  public final void remove() {
    backingIterator.remove();
  }

      protected @Nullable C computeNext() {
        while (merged.hasNext()) {
          C next = merged.next();
          boolean duplicate = lastValue != null && comparator.compare(next, lastValue) == 0;

          // Keep looping till we find a non-duplicate value.
          if (!duplicate) {
            lastValue = next;
            return lastValue;
          }
        }

///

/// info

In this example we use invented custom headers `X-Key` and `X-Token`.

But in real cases, when implementing security, you would get more benefits from using the integrated [Security utilities (the next chapter)](../security/index.md).

///

## Dependencies errors and return values { #dependencies-errors-and-return-values }

You can use the same dependency *functions* you use normally.