presto-main/src/main/java/io/prestosql/operator/aggregation/DecimalAverageAggregation.java/DecimalAverageAggregation/accumulateValueInState
class DecimalAverageAggregation:    private static void accumulateValueInState(Slice unscaledValue, LongDecimalWithOverflowAndLongState state)
    {
        accumulateAndUpdateOverflow(unscaledValue, state);
        state.setLong(state.getLong() + 1);
    }