Admin units are reviewable again after disease extent generation

How about getComparisonDate is:
return getLatest(diseaseGroup.getLastExtentGenerationDate(), diseaseGroup.getAutomaticModelRunsStartDate());

then getLatest is:

if (date1 == null) {
return date2;
} else if (date2 == null) {
return date1;
} else {
return date1.isAfter(date2) ? date1 : date2;
}