default OptionalLong totalCount() {
    if (insertedCount().isPresent() && deletedCount().isPresent() && updatedCount().isPresent()) {
      long value = insertedCount().getAsLong() + deletedCount().getAsLong() + updatedCount().getAsLong();
      return OptionalLong.of(value);
    }

    return OptionalLong.empty();
  }
Total number of changes occurred after a write operation. Sum of existing counts
if they're all defined, otherwise return {@link OptionalLong#empty()}.
criteria/common/src/org/immutables/criteria/backend/WriteResult.java