Design error annotations on Base

[mmsmits]

No description provided.

[ewoutkramer]

When we have decided, make sure we update PocoBuilderNew.cs to not throw an InvalidCastException, but handle this gracefully instead.

[ewoutkramer]

The whole intent here is to be able to let the POCO model reflect data that does not fit the POCO model. In ATL we figured that each POCO can have an error annotation to indicate that we did not REALLY find that POCO there, but something else instead (e.g. we found a list where we expected a single instance, we found a string where we expected an object etc).

After thinking about this a bit more, maybe we just need a "look at the overflow" bit in a resource, which basically enables us to "divert" from the original property to the overflow, where we can then represent everything. The reason we did not design this intitially, is that we don't want evert property to be potentially present in the overflow (it means checking to places for every access), but if we'd use just this "bit", we only need to check the bit (instead of a dict lookup) to know that we then need to do a dict lookup. But that's in error cases, and exceptional anyway.