question: public static Collection < String > nodeId8s ( @ Nullable Collection < ? extends ClusterNode > nodes ) { if ( nodes == null || nodes . isEmpty ( ) ) return Collections . emptyList ( ) ; return F . viewReadOnly ( nodes , NODE2ID8 ) ; }
target:  Convenient utility method that returns collection of node ID8s for a given collection of grid nodes. ID8 is a shorter string representation of node ID, mainly the first 8 characters. <p> Note that this method doesn't create a new collection but simply iterates over the input one.