When a method that is modeled to return an interface type is overridden in .NET, the callback handler fails to map the object to the JSII type, producing the Could not infer JSII type for .NET type error.

This is because the callback code attempts to map the type using the PrimitiveType.Any reference type instead of what is modeled on the overridden function.

This was identified as the root cause of aws/aws-cdk#1027.