private TtlUpdateRequest createTtlUpdateRequest() {
    return new TtlUpdateRequest(NonBlockingRouter.correlationIdGenerator.incrementAndGet(), routerConfig.routerHostname,
        blobId, expiresAtMs, operationTimeMs);
  }
@return a {@link TtlUpdateRequest} to send to a replica.
ambry-router/src/main/java/com/github/ambry/router/TtlUpdateOperation.java