OptionalDatasetOptionalEntityHash of the sorted (primary key, __mj_UpdatedAt) pairs, or null when it cannot be computed
(dataset configs, entities without the column). Equal hashes on two processes mean they hold
the same row versions.
Newest __mj_UpdatedAt among the rows (ISO), or null when the rows carry none.
What one engine property holds right now. See BaseEngine.GetStateCensus.