xlHeaderVersion version == 1:

```
//msgp:tuple xlMetaV2VersionHeader
type xlMetaV2VersionHeader struct {
 VersionID [16]byte  // Version UUID, raw.
 ModTime   int64     // Unix nanoseconds.
 Signature [4]byte   // Signature of metadata.
 Type      uint8     // Type if the version
 Flags     uint8
}
```

The following flags are defined:

```
const (
 FreeVersion = 1 << 0

    call: Call,
    cachedResponse: Response,
  ) {
    logWithTime("cacheConditionalHit: $cachedResponse")
  }

  private fun logWithTime(message: String) {
    val timeMs = TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startNs)
    logger.log("[$timeMs ms] $message")
  }

  open class Factory
    @JvmOverloads
    constructor(

    lastTimestampNs = result.timestampNs

    if (eventClass != null) {
      assertThat(result).isInstanceOf(eventClass)
    }

    if (elapsedMs != -1L) {
      assertThat(
        TimeUnit.NANOSECONDS.toMillis(actualElapsedNs)
          .toDouble(),
      )
        .isCloseTo(elapsedMs.toDouble(), 100.0)
    }

    return result
  }

  fun recordedEventTypes() = eventSequence.map { it.name }

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import static java.util.concurrent.TimeUnit.NANOSECONDS;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.base.Ascii;
import com.google.common.base.Equivalence;

  ): RealConnectionPool {
    return RealConnectionPool(
      taskRunner = taskRunner,
      maxIdleConnections = maxIdleConnections,
      keepAliveDuration = 100L,
      timeUnit = TimeUnit.NANOSECONDS,
      connectionListener = ConnectionListener.NONE,
      exchangeFinderFactory = { pool, address, user ->
        FastFallbackExchangeFinder(
          routePlanner ?: RealRoutePlanner(

   * @since 28.0
   */
  default void awaitRunning(Duration timeout) throws TimeoutException {
    awaitRunning(toNanosSaturated(timeout), TimeUnit.NANOSECONDS);
  }

  /**
   * Waits for the {@link Service} to reach the {@linkplain State#RUNNING running state} for no more
   * than the given time.
   *
   * @param timeout the maximum time to wait

        }

        // Wait for an in-flight connect to complete or fail.
        if (connectResult == null) {
          connectResult = awaitTcpConnect(awaitTimeoutNanos, TimeUnit.NANOSECONDS) ?: continue
        }

        if (connectResult.isSuccess) {
          // We have a connected TCP connection. Cancel and defer the racing connects that all lost.
          cancelInFlightConnects()

  public static RateLimiter create(double permitsPerSecond, Duration warmupPeriod) {
    return create(permitsPerSecond, toNanosSaturated(warmupPeriod), TimeUnit.NANOSECONDS);
  }

  /**
   * Creates a {@code RateLimiter} with the specified stable throughput, given as "permits per
   * second" (commonly referred to as <i>QPS</i>, queries per second), and a <i>warmup period</i>,

    val startNanos = System.nanoTime()
    while (webSocket.receivedPongCount() < 3) {
      Thread.sleep(50)
    }
    val elapsedUntilPong3 = System.nanoTime() - startNanos
    assertThat(TimeUnit.NANOSECONDS.toMillis(elapsedUntilPong3).toDouble())
      .isCloseTo(1500.0, 250.0)

    // The client pinged the server 3 times, and it has ponged back 3 times.
    assertThat(webSocket.sentPingCount()).isEqualTo(3)

   */
  public static RateLimiter create(double permitsPerSecond, Duration warmupPeriod) {
    return create(permitsPerSecond, toNanosSaturated(warmupPeriod), TimeUnit.NANOSECONDS);
  }

  /**
   * Creates a {@code RateLimiter} with the specified stable throughput, given as "permits per
   * second" (commonly referred to as <i>QPS</i>, queries per second), and a <i>warmup period</i>,