// shouldn't break in cases where reflection is missing/broken.
    if (thrownAtomicReferenceFieldUpdaterFailure != null) {
      log.get().log(Level.SEVERE, "UnsafeAtomicHelper is broken!", thrownUnsafeFailure);
      log.get()
          .log(
              Level.SEVERE,
              "SafeAtomicHelper is broken!",
              thrownAtomicReferenceFieldUpdaterFailure);
    }
  }

 * backing collection and the mutex are serializable.
 *
 * <p>If {@code null} is passed as the {@code mutex} parameter to any of this class's top-level
 * methods or inner class constructors, the created object uses itself as the synchronization mutex.
 *
 * <p>This class should be used by other collection classes only.
 *
 * @author Mike Bostock
 * @author Jared Levy

   */
  final transient int segmentShift;

  /** The segments, each of which is a specialized hash table. */
  final transient Segment<K, V, E, S>[] segments;

  /** The concurrency level. */
  final int concurrencyLevel;

  /** Strategy for comparing keys. */
  final Equivalence<Object> keyEquivalence;

  /** Strategy for handling entries and segments in a type-safe and efficient manner. */