}
  }

  @AndroidIncompatible // Path (for symlink creation)

  public void testScanDirectory_symlinkCycle() throws IOException {
    if (isWindows()) {
      return; // TODO: b/136041958 - Can we detect cycles under Windows?
    }
    ClassLoader loader = ClassPathTest.class.getClassLoader();
    // directory with a cycle,
    // /root
    //    /left
    //       /[sibling -> right]
    //    /right

    // load timeout multiplier.  Or we could try to use a CPU time bound instead of wall clock time
    // bound.  But these ideas are harder to implement.  We do not try to detect or handle a
    // user-specified -XX:+DisableExplicitGC.
    //
    // TODO(user): Consider using
    // java/lang/management/OperatingSystemMXBean.html#getSystemLoadAverage()
    //

      this.size += other.size;
      return this;
    }

    private ImmutableMap<K, V> build(boolean throwIfDuplicateKeys) {
      /*
       * If entries is full, or if hash flooding is detected, then this implementation may end up
       * using the entries array directly and writing over the entry objects with non-terminal
       * entries, but this is safe; if this Builder is used further, it will grow the entries array

   *       collections intelligently fall back to a binary search tree if hash table collisions are
   *       detected. Rather than going to all the trouble of reimplementing this ourselves, we
   *       simply switch over to use the JDK implementation wholesale if probable hash flooding is
   *       detected, sacrificing the compactness guarantee in very rare cases in exchange for much
   *       more reliable worst-case behavior.

 *
 * <p>{@code com.google.common.base.FinalizableReferenceQueue} loads this class in its own class
 * loader. That way, this class doesn't prevent the main class loader from getting garbage
 * collected, and this class can detect when the main class loader has been garbage collected and
 * stop itself.
 */
// no @ElementTypesAreNonNullByDefault for the reasons discussed above
public class Finalizer implements Runnable {

  // app (like the FrqUser class above), then the app's ClassLoader will never be gc'd. The reason
  // is that we attempt to run a thread in a separate ClassLoader that will detect when the FRQ
  // is no longer referenced, meaning that the app's ClassLoader has been gc'd, and when that
  // happens. But the thread's supposedly separate ClassLoader actually has a reference to the app's

   * It is possible for a Cell to become unused when threads that
   * once hashed to it terminate, as well as in the case where
   * doubling the table causes no thread to hash to it under
   * expanded mask.  We do not try to detect or remove such cells,
   * under the assumption that for long-running instances, observed
   * contention levels will recur, so the cells will eventually be
   * needed again; and for short-lived ones, it does not matter.
   */

    /*
     * Wait not just until the Future's value is set (as in future.get()) but
     * also until ListeningScheduledExecutorService's wrapper task is done
     * executing listeners, as detected by yielding control to afterExecute.
     */
    completed.await();
    assertTrue(future.isDone());
    assertThat(future.get()).isEqualTo(42);
    assertListenerRunImmediately(future);

   * 'affect' a bit(j) in the output if two inputs, identical but for bit(i), will differ at output
   * bit(j) about half the time
   *
   * <p>Funneling is pretty simple to detect. The key idea is to find example keys which
   * unequivocally demonstrate that funneling cannot be occurring. This is done bit-by-bit. For each

  }

  public void testSetIndirectSelf_toString() {
    final SettableFuture<Object> orig = SettableFuture.create();
    // unlike the above this indirection defeats the trivial cycle detection and causes a SOE
    orig.setFuture(
        new ForwardingListenableFuture<Object>() {
          @Override
          protected ListenableFuture<Object> delegate() {
            return orig;
          }