public boolean addMasks(final Collection<CustomRollUpMask> masks) {
            final List<MaskHolder> list = new ArrayList<>();

            for (final CustomRollUpMask mask : masks) {
                final MaskHolder holder = new MaskHolder(idCounter++, mask);
                list.add(holder);
            }
            return super.addAll(list);
        }
Extension of ArrayList that adds an ID value to each
{@link CustomRollUpMask} object added to it
stroom-statistics/stroom-statistics-client/src/main/java/stroom/statistics/impl/hbase/client/presenter/StroomStatsStoreCustomMaskListPresenter.java