* and https://github.com/jspecify/jspecify/issues/490.
   *
   * (That would also have ensured that its cause was always an Error, rather than possibly another
   * kind of Throwable that was later passed to initCause. Then we could have declared the override
   * `public final Error getCause()`.)
   */

  /**
   * Creates a new instance with {@code null} as its detail message and no cause.
   *

   * (used as the reference iterator) against a {@code PeekingIterator} that *wraps* such an
   * iterator (used as the target iterator).
   *
   * <p>This IteratorTester makes copies of the master so that it can later verify that {@link
   * PeekingIterator#remove()} removes the same elements as the reference's iterator {@code
   * #remove()}.
   */

  protected Queue<String> create() {
    TestQueue<String> inner = new TestQueue<>();
    Queue<String> outer = Synchronized.queue(inner, inner.mutex);
    outer.add("foo"); // necessary because we try to remove elements later on
    return outer;
  }

  private static final class TestQueue<E> implements Queue<E> {
    private final Queue<E> delegate = Lists.newLinkedList();

   * having a hash table of size eight. Providing a large enough estimate at construction time
   * avoids the need for expensive resizing operations later, but setting this value unnecessarily
   * high wastes memory.
   *
   * @throws IllegalArgumentException if {@code initialCapacity} is negative
   * @throws IllegalStateException if an initial capacity was already set

   * listeners for future n may complete before some for future n-1.) However, it is possible, if
   * one input completes with result X and another later with result Y, for Y to come before X in
   * the output future list. (Such races are impossible to solve without global synchronization of
   * all future completions. And they should have little practical impact.)
   *

      // It's possible to keep using this Builder after calling buildKeepingLast(), so we need to
      // ensure that its state is not corrupted by removing duplicates that should cause a later
      // buildOrThrow() to fail, or by changing the size.
      @Nullable Entry<K, V>[] localEntries;
      int localSize = size;
      if (valueComparator == null) {
        localEntries = entries;
      } else {

 * #runOneIteration} takes longer than its schedule defines, then subsequent executions may start
 * late. Also, all life cycle methods are executed with a lock held, so subclasses can safely modify
 * shared state without additional synchronization necessary for visibility to later executions of
 * the life cycle methods.
 *
 * <h3>Usage Example</h3>
 *

   *
   * A call to of() with a parameter that is not a plain Object[] (here,
   * Interface[]) creates a RegularImmutableSortedSet backed by an array of that
   * type. Later, RegularImmutableSortedSet.toArray() calls System.arraycopy()
   * to copy from that array to the destination array. This would be fine, but
   * GWT has a bug: It refuses to copy from an E[] to an Object[] when E is an

    return JavaDigit.INSTANCE;
  }

  /**
   * Determines whether a character is a BMP letter according to {@linkplain
   * Character#isLetter(char) Java's definition}. If you only care to match letters of the Latin
   * alphabet, you can use {@code inRange('a', 'z').or(inRange('A', 'Z'))}.
   *
   * @deprecated Most letters are supplementary characters; see the class documentation.

   * having a hash table of size eight. Providing a large enough estimate at construction time
   * avoids the need for expensive resizing operations later, but setting this value unnecessarily
   * high wastes memory.
   *
   * @return this {@code CacheBuilder} instance (for chaining)
   * @throws IllegalArgumentException if {@code initialCapacity} is negative