fix: RWClass returns empty outer class

assira.core/src/main/java/net/ranides/assira/reflection/impl/RWClass.java

@@ -86,7 +86,12 @@ public class RWClass<T> extends AClass<T> implements Serializable {
     IClass<?>[] lower() {
         return lower;
     }
-    
+
+    @Override
+    public IClass<?> outer() {
+        return NULL;
+    }
+
     @Override
     public IClass<?> parent() {
         return FElements.newClasses(upper).discard(IAttribute.INTERFACE).first().get();