public Optional<Long> sizeIfKnown() {
      if (!(sources instanceof Collection)) {
        // Infinite Iterables can cause problems here. Of course, it's true that most of the other
        // methods on this class also have potential problems with infinite  Iterables. But unlike
        // those, this method can cause issues even if the user is dealing with a (finite) slice()

    checkFromStringCase("google.com:25\t", 1, null, 99, false);
    checkFromStringCase("google.com:0x25 ", 1, null, 99, false);
  }

  public void testFromStringUnparseableNonsense() {
    // Some nonsense that causes parse failures.
    checkFromStringCase("[goo.gl]", 1, null, 99, false);
    checkFromStringCase("[goo.gl]:80", 1, null, 99, false);
    checkFromStringCase("[", 1, null, 99, false);

    assertEquals(Arrays.toString(events), stopwatch.readEventsAndClear());
  }

  /**
   * The stopwatch gathers events and presents them as strings. R0.6 means a delay of 0.6 seconds
   * caused by the (R)ateLimiter U1.0 means the (U)ser caused the stopwatch to sleep for a second.
   */
  static class FakeStopwatch extends SleepingStopwatch {
    long instant = 0L;
    final List<String> events = Lists.newArrayList();

    for (int i = 0; i < position; i++) {
      iterator.next();
    }
    return iterator.next();
  }

  static void fail(Throwable cause, Object message) {
    AssertionFailedError assertionFailedError = new AssertionFailedError(String.valueOf(message));
    assertionFailedError.initCause(cause);
    throw assertionFailedError;
  }

  private static class EntryComparator<K extends @Nullable Object, V extends @Nullable Object>

    };
  }

  /** Alternative to AssertionError(String, Throwable), which doesn't exist in Java 1.6 */
  private static AssertionError newAssertionError(String message, Throwable cause) {
    AssertionError e = new AssertionError(message);
    e.initCause(cause);
    return e;
  }

   * observed contention rates are typically low in these cases.
   *
   * 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

 * {@code ContiguousSet.create(Range.greaterThan(0), DiscreteDomain.integers()}). Certain operations
 * on such a set can be performed efficiently, but others (such as {@link Set#hashCode} or {@link
 * Collections#frequency}) can cause major performance problems.
 *
 * @author Gregory Kick
 * @since 10.0
 */
@GwtCompatible(emulated = true)
@SuppressWarnings("rawtypes") // allow ungenerified Comparable types
@ElementTypesAreNonnullByDefault

@GwtCompatible(emulated = true)
@ReflectionSupport(value = ReflectionSupport.Level.FULL)
@ElementTypesAreNonnullByDefault
// Some Android 5.0.x Samsung devices have bugs in JDK reflection APIs that cause
// getDeclaredField to throw a NoSuchFieldException when the field is definitely there.
// Since this class only needs CAS on one field, we can avoid this bug by extending AtomicReference

      return builder.build();
    }
  }

  public static class ImmutableSetWithBadHashesGenerator extends TestCollidingSetGenerator
      // Work around a GWT compiler bug.  Not explicitly listing this will
      // cause the createArray() method missing in the generated javascript.
      // TODO: Remove this once the GWT bug is fixed.
      implements TestCollectionGenerator<Object> {
    @Override

    failLeave.countDown(); // release the background thread
  }

  /**
   * Catches a bug where when constructing a service manager failed, later interactions with the
   * service could cause IllegalStateExceptions inside the partially constructed ServiceManager.
   * This ISE wouldn't actually bubble up but would get logged by ExecutionQueue. This obfuscated