question: private List < Long > addNegativeBuckets ( List < Long > bucketList ) { logger . debug ( "Adding negative buckets..." ) ; List < Long > negBuckets = new ArrayList < > ( bucketList . size ( ) ) ; int counter = 0 ; for ( Long l : bucketList ) { if ( l . longValue ( ) != 0 ) { negBuckets . add ( l * - 1 ) ; if ( counter % 1000 == 0 ) { logger . debug ( "Added -" + l + " from index: " + counter ) ; } counter ++ ; } } logger . debug ( "Negative buckets generated." ) ; negBuckets . addAll ( bucketList ) ; logger . debug ( "Negative buckets added." ) ; logger . debug ( "Done adding negative buckets..." ) ; return negBuckets ; }
target:  Adds a mirrored version of the bucket list, but with negative values.