question: @ 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 ) ; }
target:  Gets topology by specified version from history storage.