presto-orc/src/main/java/io/prestosql/orc/OrcWriteValidation.java/OrcWriteValidation/RowGroupStatistics
class OrcWriteValidation:        public RowGroupStatistics(OrcWriteValidationMode validationMode, Map<OrcColumnId, ColumnStatistics> columnStatistics)
        {
            this.validationMode = validationMode;

            requireNonNull(columnStatistics, "columnStatistics is null");
            if (validationMode == HASHED) {
                this.columnStatistics = ImmutableSortedMap.of();
                hash = hashColumnStatistics(ImmutableSortedMap.copyOf(columnStatistics));
            }
            else if (validationMode == DETAILED) {
                this.columnStatistics = ImmutableSortedMap.copyOf(columnStatistics);
                hash = 0;
            }
            else if (validationMode == BOTH) {
                this.columnStatistics = ImmutableSortedMap.copyOf(columnStatistics);
                hash = hashColumnStatistics(this.columnStatistics);
            }
            else {
                throw new IllegalArgumentException("Unsupported validation mode");
            }
        }