question: public void merge ( final JournalTransaction other ) { if ( other . pos != null ) { if ( pos == null ) { pos = new ArrayList < > ( ) ; } pos . addAll ( other . pos ) ; } if ( other . neg != null ) { if ( neg == null ) { neg = new ArrayList < > ( ) ; } neg . addAll ( other . neg ) ; } if ( other . pendingFiles != null ) { if ( pendingFiles == null ) { pendingFiles = new HashSet < > ( ) ; } pendingFiles . addAll ( other . pendingFiles ) ; } compacting = false ; }
target:  This is used to merge transactions from compacting