add subtyping checks for side variance

Author: FelixAnthonisen

src/main/java/io/github/bldl/astParsing/visitors/SubtypingCheckVisitor.java

@@ -197,6 +197,9 @@ private boolean isValidSubtype(ClassOrInterfaceType assigneeType, ClassOrInterfa
                         return classHierarchy.isDescendant(
                                 ((ClassOrInterfaceType) assignedArgs.get(i)).getNameAsString(),
                                 ((ClassOrInterfaceType) assigneeArgs.get(i)).getNameAsString(), mp.get(i).depth());
+                    case SIDE:
+                        return classHierarchy.sameLevel(((ClassOrInterfaceType) assignedArgs.get(i)).getNameAsString(),
+                                ((ClassOrInterfaceType) assigneeArgs.get(i)).getNameAsString());
                     default:
                         return false;
                 }