The domain of genericity of an existing generic class may be expanded to include not just reference types, but also primitive and value types even though some members of the existing class do not support the expanded genericity. A subdivided version of the class may be created that includes a generic layer including abstract versions of class members and a reference-specific layer that including non-abstract versions of class members that are abstract in the generic layer. The subdivided version of the class may also include information that indicates to which layer a class member belongs. Problematic methods (e.g., methods that have built-in assumptions regarding the domain of genericity) may be moved into the second, reference-specific, layer, thereby retaining compatibility with classes that currently instantiate or reference those methods, while still allowing use within the expanded domain of genericity.