public static class Parts
    {
        private final Optional<StatisticAggregations> finalAggregation;
        private final Optional<StatisticAggregations> intermediateAggregation;
        private final StatisticAggregations partialAggregation;

        public Parts(
                Optional<StatisticAggregations> finalAggregation,
                Optional<StatisticAggregations> intermediateAggregation,
                StatisticAggregations partialAggregation)
        {
            this.finalAggregation = requireNonNull(finalAggregation, "finalAggregation is null");
            this.intermediateAggregation = requireNonNull(intermediateAggregation, "intermediateAggregation is null");
            this.partialAggregation = requireNonNull(partialAggregation, "partialAggregation is null");
        }

        public StatisticAggregations getFinalAggregation()
        {
            return finalAggregation.orElseThrow(() -> new IllegalStateException("finalAggregation is not present"));
        }

        public StatisticAggregations getIntermediateAggregation()
        {
            return intermediateAggregation.orElseThrow(() -> new IllegalStateException("intermediateAggregation is not present"));
        }

        public StatisticAggregations getPartialAggregation()
        {
            return partialAggregation;
        }
    }