Fix EA-42958 - ISE: FqName.parent

compiler/frontend.java/src/org/jetbrains/jet/lang/resolve/java/PackageClassUtils.java

@@ -42,4 +42,11 @@ public class PackageClassUtils {
     public static boolean isPackageClass(@NotNull PsiClass psiClass) {
         return JetPackageClassAnnotation.get(psiClass).isDefined();
     }
+
+    public static boolean isPackageClass(@NotNull FqName fqName) {
+        if (fqName.isRoot()) {
+            return false;
+        }
+        return PackageClassUtils.getPackageClassFqName(fqName.parent()).equals(fqName);
+    }
 }

compiler/jet.as.java.psi/src/org/jetbrains/jet/asJava/JavaElementFinder.java

@@ -87,9 +87,8 @@ public class JavaElementFinder extends PsiElementFinder implements JavaPsiFacade
 
         findClassesAndObjects(qualifiedName, scope, answer);
 
-        FqName packageFQN = qualifiedName.parent();
-        if (PackageClassUtils.getPackageClassFqName(packageFQN).equals(qualifiedName)) {
-            findPackageClass(packageFQN, scope, answer);
+        if (PackageClassUtils.isPackageClass(qualifiedName)) {
+            findPackageClass(qualifiedName.parent(), scope, answer);
         }
 
         return answer.toArray(new PsiClass[answer.size()]);