I am working on some code using the EMF framework in Java, but it is really hard to use, e.g. I cannot implement OCL-like query API on top of EMF which would be type-safe.
One of the reasons is that eGet() for a EStructuralFeature returns just an Object, not EObject. So anything I would write must use much of null checking, type checking and type casting which is unsafe, not performant and cannot be generalized in a reusable way.
Why doesn't EMF generate dummy implementations with EObject wrappers for arbitrary Object value?
Implementing the EObject and hence the EClass interfaces even with simple throw UnsupportedOperationException is really a pain (the APIs are too big). The same holds for the eContainer() method which makes navigating the model upwards painful.
The same method is used for accessing simple attribute values (which can be of any Java type) and traverse relationships to other modeled objects, and those can be single or multivalued.
EMF provides generic mechanisms for checking whether an object is an instance of an EClass, or if an EClass is assignable to another, so I don't really see the problem with that.