@Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + mask;
        result = prime * result + Arrays.hashCode(maskAsBytes);
        return result;
    }
Output has mask position zero on the right
stroom-statistics/stroom-statistics-impl-sql/src/main/java/stroom/statistics/impl/sql/rollup/RollUpBitMask.java