Thanks for let us know your question.
We get its value from the table in FileGeoDatabase, follow the standard, each table should only contains one shape type.
For our FileGeoDatabaseFeatureLayer, it have an active layer(active table, by default it is the first table), the ((FileGeoDatabaseFeatureSource)layer.FeatureSource).GetWellKnownType() return the type of active layer. Here is a screen shot from other utility, you can see the geometry type is related with table(active layer).
The value of ObjectID is saved into feature.ID but not FEATUREID, you can found the FEATUREID is still in column values.
It’s not in column values now is because the behavior change in the new library we chosen.
var cAllFeatures = fileGeoDatabaseFeatureLayer.FeatureSource.GetAllFeatures(ReturningColumnsType.AllColumns);
foreach (Feature TheFeature in cAllFeatures)
var objectID = TheFeature.Id;
I hope that’s helpful.