@Override
    public boolean equals(final Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final RollUpBitMask other = (RollUpBitMask) obj;
        if (mask != other.mask) {
            return false;
        }
        return Arrays.equals(maskAsBytes, other.maskAsBytes);
    }
Output has mask position zero on the right
stroom-statistics/stroom-statistics-impl-hbase/src/main/java/stroom/statistics/impl/hbase/rollup/RollUpBitMask.java