@Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((originalStatisticEvent == null)
                ? 0
                : originalStatisticEvent.hashCode());
        result = prime * result + ((tagListPermutations == null)
                ? 0
                : tagListPermutations.hashCode());
        return result;
    }
To be used when no roll ups are required
stroom-statistics/stroom-statistics-impl-sql/src/main/java/stroom/statistics/impl/sql/rollup/RolledUpStatisticEvent.java