InputLocationTracker tracker) {
        if (!validateNotNull(prefix, fieldName, problems, severity, version, string, sourceHint, tracker)) {
            return false;
        }

        if (!string.isEmpty()) {
            return true;
        }

        addViolation(problems, severity, version, prefix + fieldName, sourceHint, "is missing.", tracker);

        return false;
    }

  public void testAdvance() {
    FakeTicker ticker = new FakeTicker();
    assertEquals(0, ticker.read());
    assertSame(ticker, ticker.advance(10));
    assertEquals(10, ticker.read());
    ticker.advance(1, TimeUnit.MILLISECONDS);
    assertEquals(1000010L, ticker.read());
    ticker.advance(Duration.ofMillis(1));
    assertEquals(2000010L, ticker.read());
  }

  public void testAutoRefresh() {
    FakeTicker ticker = new FakeTicker();
    IncrementingLoader loader = incrementingLoader();
    LoadingCache<Integer, Integer> cache =
        CacheBuilder.newBuilder()
            .refreshAfterWrite(3, MILLISECONDS)
            .expireAfterWrite(6, MILLISECONDS)
            .lenientParsing()
            .ticker(ticker)
            .build(loader);
    int expectedLoads = 0;

  }

  public void testTicker_setTwice() {
    Ticker testTicker = Ticker.systemTicker();
    CacheBuilder<Object, Object> builder = CacheBuilder.newBuilder().ticker(testTicker);
    try {
      // even to the same instance is not allowed
      builder.ticker(testTicker);
      fail();
    } catch (IllegalStateException expected) {
    }
  }

    private static final String PLAY_SERVER_PATTERN_STR = "(play\\.core\\.server\\.NettyServer)";
    private static final String JAVA_PROCESS_STACK_TRACES_MONITOR_PATTERN_STR = "(JavaProcessStackTracesMonitor\\.java)";
    private static ExecutionMode executionMode;

    static String generateAllGradleProcessPattern() {

    assertEquals("valueStrength", a.valueStrength, b.valueStrength);
    assertEquals("statsCounterSupplier", a.statsCounterSupplier, b.statsCounterSupplier);
    assertEquals("ticker", a.ticker, b.ticker);
    assertEquals("recordStats", a.isRecordingStats(), b.isRecordingStats());
  }

      @Override
      public String toString() {
        return string;
      }
    };
  }

  @Generates
  Ticker generateTicker() {
    return new Ticker() {
      @Override
      public long read() {
        return 0;
      }

      final String string = paramString(Ticker.class, generateInt());

      @Override
      public String toString() {
        return string;
      }
    };

 * named analogously to their {@code BigInteger} counterparts.
 *
 * <p>The implementations of many methods in this class are based on material from Henry S. Warren,
 * Jr.'s <i>Hacker's Delight</i>, (Addison Wesley, 2002).
 *
 * <p>Similar functionality for {@code long} and for {@link BigInteger} can be found in {@link
 * LongMath} and {@link BigIntegerMath} respectively. For other common operations on {@code int}

@ElementTypesAreNonnullByDefault
public abstract class Ticker {
  /** Constructor for use by subclasses. */
  protected Ticker() {}

  /** Returns the number of nanoseconds elapsed since this ticker's fixed point of reference. */
  public abstract long read();

  /**
   * A ticker that reads the current time using {@link System#nanoTime}.
   *
   * @since 10.0
   */
  public static Ticker systemTicker() {
    return SYSTEM_TICKER;
  }

   * to produce warnings in that case, and we may change this method to do so in the future. Support
   * for raw {@code Comparable} types in Guava in general is tracked as <a
   * href="https://github.com/google/guava/issues/989">#989</a>.)
   *
   * @throws ClassCastException if the parameters are not mutually comparable
   */