@Nullable public Collection<ClusterNode> topology(long topVer){
  if (!histSupported)   throw new UnsupportedOperationException("Current discovery SPI does not support " + "topology snapshots history (consider using TCP discovery SPI).");
  Map<Long,Collection<ClusterNode>> snapshots=topHist;
  return snapshots.get(topVer);
}

@ Nullable public Collection < ClusterNode > topology ( long topVer ) { if ( ! histSupported ) throw new UnsupportedOperationException ( "Current discovery SPI does not support " + "topology snapshots history (consider using TCP discovery SPI)." ) ; Map < Long , Collection < ClusterNode > > snapshots = topHist ; return snapshots . get ( topVer ) ; }
gets topology by specified version from history storage .
