* Loads {@link WillBeUnloadedException} in a separate {@code ClassLoader}, calls {@code
   * getChecked(future, WillBeUnloadedException.class)}, and returns the loader. The caller can then
   * test that the {@code ClassLoader} can still be GCed. The test amounts to a test that {@code
   * getChecked} holds no strong references to the class.
   */
  private WeakReference<?> doTestClassUnloading() throws Exception {

    }

    // Android isolates apps' temporary directories since Jelly Bean:
    // https://github.com/google/guava/issues/4011#issuecomment-770020802
    // So we can create files there with any permissions and still get security from the isolation.
    return new JavaIoCreator();
  }

  /**
   * Creates the permissions normally used for Windows filesystems, looking up the user afresh, even

 * 
 * Be advised that short/NetBIOS name usage is not supported with this authenticator. Always specify full FQDNs.
 * This can be a problem if using DFS in it's default configuration as they still return referrals in short form.
 * See <a href="https://support.microsoft.com/en-us/kb/244380">KB-244380</a> for compatible server configuration.
 * See {@link jcifs.Configuration#isDfsConvertToFQDN()} for a workaround.
 */

            Arrays.asList(ValidationReportLevel.INLINE, ValidationReportLevel.BRIEF));

    private enum ValidationReportLevel {
        NONE, // mute validation completely (validation issue collection still happens, it is just not reported!)
        INLINE, // inline, each "internal" problem one line next to mojo invocation
        SUMMARY, // at end, list of plugin GAVs along with ANY validation issues

 *             loadExceptionCount} are incremented, and the total loading time, in nanoseconds, is
 *             added to {@code totalLoadTime}.
 *         <li>Cache lookups that encounter a missing cache entry that is still loading will wait
 *             for loading to complete (whether successful or not) and then increment {@code
 *             missCount}.
 *       </ul>

            + "exposed by the superclass implementation. If the implementation has "
            + "changed, the code must be re-inspected to ensure that the "
            + "assumption is still valid.",
        24,
        ReentrantReadWriteLock.class.getMethods().length);
  }

  private enum MyOrder {
    FIRST,
    SECOND,
    THIRD;
  }

  private enum OtherOrder {

  // security reasons anyway. Therefore, the FRQ.close() method provides a way to stop the thread
  // explicitly. This test checks that calling that method does allow an app's ClassLoader to be
  // gc'd even if there is a still a FinalizableReferenceQueue in a static field. (Setting the field
  // to null would also work, but only if there are no references to the FRQ anywhere else.)

 *             loadExceptionCount} are incremented, and the total loading time, in nanoseconds, is
 *             added to {@code totalLoadTime}.
 *         <li>Cache lookups that encounter a missing cache entry that is still loading will wait
 *             for loading to complete (whether successful or not) and then increment {@code
 *             missCount}.
 *       </ul>

   * There is no need for a blocking lock; when the lock is not
   * available, threads try other slots (or the base).  During these
   * retries, there is increased contention and reduced locality,
   * which is still better than alternatives.
   *
   * Per-thread hash codes are initialized to random values.
   * Contention and/or table collisions are indicated by failed
   * CASes when performing an update operation (see method

 */
@ElementTypesAreNonnullByDefault
final class DirectedGraphConnections<N, V> implements GraphConnections<N, V> {
  /**
   * A wrapper class to indicate a node is both a predecessor and successor while still providing
   * the successor value.
   */
  private static final class PredAndSucc {
    private final Object successorValue;

    PredAndSucc(Object successorValue) {
      this.successorValue = successorValue;