release_date after ontology update

[piotr-florek-mohc]

Hi,
In the process of rebuilding our MOHC model documentation I have updated the pyesdoc library, and did a quick 2to3 run to upgrade the code to Python 3. The good news is that everything seems to be working fine, with one small exception: in the 2.2 ontology update the release_date field (in the software classes) was changed from standard datetime to cim.v2.DateTime (here and here). Could you please confirm that was intentional change? I used to think that this type is more related to internal representation of time axis in netCDF4 output, but my understanding of CIMv2 is very limited and I might be confused about it.

(Anyway, the field is optional, so I can generate model documents without it just fine)