For AdaptDDL OnEnrollBreak=WARNING :

Default behavior is to not drop/recreate target table and refresh it. This works well for us when we add a NULL column on source as logically this doesnt need the target to be dropped/re-created and refreshed but testing the same for not NULL column addtion with a default has a risk of introducing data discrepancy by disallowing table refresh. 

Example : If a not null int column is added on source with say default 999 value, on the WARNING AdaptDDL setting, the column is added to the target without refresh and with default value of 0.  So all existing rows in the target are now out of sync to source as the default value stamped is different. 

We have tested multiple scenarios and seen that certain DDL types on this WARNING mode do trigger refreshes like column expansion so we wanted to request to get the not null added to exception code path and trigger a refresh as we want to leverage the WARNING mode. 

Context to use WARNING mode - We have an environment where we have setup AdaptDDL on source/target on default mode which then poses a risk of having data refresh for null column additions which are pretty frequent and for large tables then this becomes a problem. So we were advised by FT to leverage WARNING which will disallow the refreshes but on our testing (described above) we see high probability of data discrepancy hence the request which seems to be a fair ask else it defeats the purpose of maintaining consistency between source and targets.