@Override
  public RouterConfig getRouterConfig() {
    return routerConfig;
  }
Requests that a blob's TTL be updated asynchronously and returns a future that will eventually contain information
about whether the request succeeded or not.

@param restRequest The {@link RestRequest} of updateBlobTtl
@param blobId      The ID of the blob that needs its TTL updated.
@param serviceId   The service ID of the service updating the blob. This can be null if unknown.
@param expiresAtMs The new expiry time (in ms) of the blob. Using {@link Utils#Infinite_Time} makes the blob
                   permanent
@param callback    The {@link Callback} which will be invoked on the completion of a request.
@return A future that would contain information about whether the update succeeded or not, eventually.
ambry-router/src/main/java/com/github/ambry/router/NonBlockingRouter.java