question: public static Map < UUID , Collection < ClusterNode > > neighbors ( Collection < ClusterNode > topSnapshot ) { Map < String , Collection < ClusterNode > > macMap = new HashMap < > ( topSnapshot . size ( ) , 1.0f ) ; for ( ClusterNode node : topSnapshot ) { String macs = node . attribute ( IgniteNodeAttributes . ATTR_MACS ) ; Collection < ClusterNode > nodes = macMap . get ( macs ) ; if ( nodes == null ) macMap . put ( macs , nodes = new HashSet < > ( ) ) ; nodes . add ( node ) ; } Map < UUID , Collection < ClusterNode > > neighbors = new HashMap < > ( topSnapshot . size ( ) , 1.0f ) ; for ( Collection < ClusterNode > group : macMap . values ( ) ) for ( ClusterNode node : group ) neighbors . put ( node . id ( ) , group ) ; return neighbors ; }
target:  Builds neighborhood map for all nodes in snapshot.