question: @ Nullable public TcpDiscoveryNode nextNode ( @ Nullable Collection < TcpDiscoveryNode > excluded ) { assert locNode . internalOrder ( ) > 0 : locNode ; assert excluded == null || excluded . isEmpty ( ) || ! excluded . contains ( locNode ) : excluded ; rwLock . readLock ( ) . lock ( ) ; try { Collection < TcpDiscoveryNode > filtered = serverNodes ( excluded ) ; if ( filtered . size ( ) < 2 ) return null ; Iterator < TcpDiscoveryNode > iter = filtered . iterator ( ) ; while ( iter . hasNext ( ) ) { TcpDiscoveryNode node = iter . next ( ) ; if ( locNode . equals ( node ) ) break ; } return iter . hasNext ( ) ? iter . next ( ) : F . first ( filtered ) ; } finally { rwLock . readLock ( ) . unlock ( ) ; } }
target:  Finds next node in the topology filtering excluded nodes from search. <p> This may be used when detecting and handling nodes failure.