code: @Override
      public boolean shouldAllowAccess(boolean remoteRegionRequired) {
          if (this.peerInstancesTransferEmptyOnStartup) {
              if (!(System.currentTimeMillis() > this.startupTime + serverConfig.getWaitTimeInMsWhenSyncEmpty())) {
                  return false;
              }
          }
          if (remoteRegionRequired) {
              for (RemoteRegionRegistry remoteRegionRegistry : this.regionNameVSRemoteRegistry.values()) {
                  if (!remoteRegionRegistry.isReadyForServingData()) {
                      return false;
                  }
              }
          }
          return true;
      }
docs: Checks to see if the registry access is allowed or the server is in a
  situation where it does not all getting registry information. The server
  does not return registry information for a period specified in
  {@link EurekaServerConfig#getWaitTimeInMsWhenSyncEmpty()}, if it cannot
  get the registry information from the peer eureka nodes at start up.
  
  @return false - if the instances count from a replica transfer returned
  zero and if the wait time has not elapsed, otherwise returns true