Contains information about object modification result; primarily needed by repository caching algorithms.
Because it is bound to the current (SQL) implementation of the repository, avoid using this information
for any other purposes.
Note that objectBefore and objectAfter might be null if the object XML representation was not changed.
It is currently the case for lookup tables (when rows are modified) and certification campaigns (when cases are modified).
In all other cases these are non-null.
EXPERIMENTAL. We will probably drop objectBefore and modifications.