docs: StatsData getAggregateStats() {
          Set<StatsData> dataSet = new HashSet<StatsData>();
          synchronized (allReferences) {
              dataSet.add(terminatedThreadStats.get().getCopy());
              for (StatsDataReference ref : allReferences) {
                  dataSet.add(ref.statsData.getCopy());
              }
          }
          cleanup();
          return aggregateStats(dataSet);
      }