private SortedSet<JClassType> computeOperableTypes(ResourceContext context) {
TypeOracle typeOracle = context.getGeneratorContext().getTypeOracle();
JClassType baseInterface = typeOracle.findType(CssResource.class.getCanonicalName());
SortedSet<JClassType> toReturn = new TreeSet<JClassType>(new JClassOrderComparator());
JClassType[] cssResourceSubtypes = baseInterface.getSubtypes();
for (JClassType type : cssResourceSubtypes) {
if (type.isInterface() != null) {
toReturn.add(type);