return nil
	}

	return objLayer
}

// ClusterCheckHandler returns if the server is ready for requests.
func ClusterCheckHandler(w http.ResponseWriter, r *http.Request) {
	ctx := newContext(r, w, "ClusterCheckHandler")

	objLayer := checkHealth(w)
	if objLayer == nil {
		return
	}

	ctx, cancel := context.WithTimeout(ctx, globalAPIConfig.getClusterDeadline())
	defer cancel()

  @Override
  public int size() {
    return size;
  }

  @Override
  public boolean isEmpty() {
    return head == null;
  }

  @Override
  public boolean containsKey(@CheckForNull Object key) {
    return keyToKeyList.containsKey(key);
  }

  @Override
  public boolean containsValue(@CheckForNull Object value) {
    return values().contains(value);
  }

 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},
 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)

 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},
 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)

 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},
 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)

 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},
 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)

 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},
 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)

 *
 * <ul>
 *   <li>methods whose return type is a type variable but which can never return {@code null},
 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)

    ): T? {
      taskRunner.lock.withLock {
        val waitUntil = nanoTime + unit.toNanos(timeout)
        while (true) {
          val result = poll()
          if (result != null) return result
          if (nanoTime >= waitUntil) return null
          val editCountBefore = editCount
          yieldUntil { nanoTime >= waitUntil || editCount > editCountBefore }
        }
      }
    }

    inverse = forward;
  }

  @Override
  protected Map<K, V> delegate() {
    return delegate;
  }

  /** Returns its input, or throws an exception if this is not a valid key. */
  @CanIgnoreReturnValue
  @ParametricNullness
  K checkKey(@ParametricNullness K key) {
    return key;
  }

  /** Returns its input, or throws an exception if this is not a valid value. */
  @CanIgnoreReturnValue