*
 * <p>Note to maintainers: This implementation relies on signed arithmetic being bit-wise equivalent
 * to unsigned arithmetic in all cases except:
 *
 * <ul>
 *   <li>comparisons (signed values can be negative)
 *   <li>division (avoided here)
 *   <li>shifting (right shift must be unsigned)
 * </ul>
 *
 * @author Kyle Maddison
 * @author Geoff Pike
 */
@ElementTypesAreNonnullByDefault

 *
 * <p><b>Note:</b> by default, the returned cache uses equality comparisons (the {@link
 * Object#equals equals} method) to determine equality for keys or values. However, if {@link
 * #weakKeys} was specified, the cache uses identity ({@code ==}) comparisons instead for keys.
 * Likewise, if {@link #weakValues} or {@link #softValues} was specified, the cache uses identity
 * comparisons for values.
 *

 *
 * <p><b>Note:</b> by default, the returned cache uses equality comparisons (the {@link
 * Object#equals equals} method) to determine equality for keys or values. However, if {@link
 * #weakKeys} was specified, the cache uses identity ({@code ==}) comparisons instead for keys.
 * Likewise, if {@link #weakValues} or {@link #softValues} was specified, the cache uses identity
 * comparisons for values.
 *

   * generated using this are byte-wise identical to those created using the C++ version, but note
   * that this uses unsigned integers (see {@link com.google.common.primitives.UnsignedInts}).
   * Comparisons between the two should take this into account.
   *
   * <p>Fingerprint2011() is a form of Murmur2 on strings up to 32 bytes and a form of CityHash for

   * thread.
   */
  private static final class ThreadConfinedTaskQueue {
    /**
     * This field is only used for identity comparisons with the current thread. Field assignments
     * are atomic, but do not provide happens-before ordering; however:
     *
     * <ul>

    // Since the last element of the heap is from the bottom level, we
    // optimistically fill index position with elements from lower levels,
    // moving the hole down. In most cases this reduces the number of
    // comparisons with toTrickle, but in some cases we will need to bubble it
    // all the way up again.
    int vacated = heap.fillHoleAt(index);
    // Try to see if toTrickle can be bubbled up min levels.

 *
 * <p><b>Java 8+ users:</b> several common uses for this class are now more comprehensively
 * addressed by the new {@link java.util.stream.Stream} library. Read the method documentation below
 * for comparisons. This class is not being deprecated, but we gently encourage you to migrate to
 * streams.
 *
 * <p><i>Performance notes:</i> Unless otherwise noted, all of the iterables produced in this class

 * should rarely override other methods.
 *
 * @author Sven Mawson
 * @author Luke Sandberg
 * @since 1.0
 */
@SuppressWarnings({
  "ShortCircuitBoolean", // we use non-short circuiting comparisons intentionally
  "nullness", // TODO(b/147136275): Remove once our checker understands & and |.
})
@GwtCompatible(emulated = true)
@ReflectionSupport(value = ReflectionSupport.Level.FULL)
@ElementTypesAreNonnullByDefault

 *       .result();
 * }
 * }</pre>
 *
 * <p>The value of this expression will have the same sign as the <i>first nonzero</i> comparison
 * result in the chain, or will be zero if every comparison result was zero.
 *
 * <p><b>Note:</b> {@code ComparisonChain} instances are <b>immutable</b>. For this utility to work
 * correctly, calls must be chained as illustrated above.
 *

 * all cases, this implementation uses {@link Comparable#compareTo} or {@link Comparator#compare}
 * instead of {@link Object#equals} to determine equivalence of instances.
 *
 * <p><b>Warning:</b> The comparison must be <i>consistent with equals</i> as explained by the
 * {@link Comparable} class specification. Otherwise, the resulting multiset will violate the {@link