PSI is just a tree with getters in Kotlin

compiler/frontend/src/org/jetbrains/jet/lang/psi/JetClass.java

 package org.jetbrains.jet.lang.psi;
 
 import com.intellij.lang.ASTNode;
-import com.intellij.psi.util.PsiTreeUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.JetNodeTypes;
@@ -105,17 +104,6 @@ public class JetClass extends JetTypeParameterListOwner implements JetClassOrObj
         return body.getProperties();
     }
 
-    public String getFQName() {
-        JetNamedDeclaration parent = PsiTreeUtil.getParentOfType(this, JetNamespace.class, JetClass.class);
-        if (parent instanceof JetNamespace) {
-            return ((JetNamespace) parent).getFQName() + "." + getName();
-        }
-        if (parent instanceof JetClass) {
-            return ((JetClass) parent).getFQName() + "." + getName();
-        }
-        return getName();
-    }
-
     public boolean isTrait() {
         return findChildByType(JetTokens.TRAIT_KEYWORD) != null;
     }

idea/src/org/jetbrains/jet/plugin/run/JetRunConfigurationProducer.java

@@ -8,7 +8,11 @@ import com.intellij.openapi.module.Module;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
-import org.jetbrains.jet.lang.psi.*;
+import com.intellij.psi.util.PsiTreeUtil;
+import org.jetbrains.jet.lang.psi.JetClass;
+import org.jetbrains.jet.lang.psi.JetFile;
+import org.jetbrains.jet.lang.psi.JetNamedDeclaration;
+import org.jetbrains.jet.lang.psi.JetNamespace;
 import org.jetbrains.jet.plugin.JetMainDetector;
 
 /**
@@ -21,6 +25,17 @@ public class JetRunConfigurationProducer extends RuntimeConfigurationProducer im
         super(JetRunConfigurationType.getInstance());
     }
 
+    private static String getFQName(JetClass jetClass) {
+        JetNamedDeclaration parent = PsiTreeUtil.getParentOfType(jetClass, JetNamespace.class, JetClass.class);
+        if (parent instanceof JetNamespace) {
+            return ((JetNamespace) parent).getFQName() + "." + jetClass.getName();
+        }
+        if (parent instanceof JetClass) {
+            return getFQName(((JetClass) parent)) + "." + jetClass.getName();
+        }
+        return jetClass.getName();
+    }
+
     @Override
     public PsiElement getSourceElement() {
         return mySourceElement;
@@ -31,7 +46,7 @@ public class JetRunConfigurationProducer extends RuntimeConfigurationProducer im
         JetClass containingClass = (JetClass) location.getParentElement(JetClass.class);
         if (containingClass != null && JetMainDetector.hasMain(containingClass.getDeclarations())) {
             mySourceElement = containingClass;
-            return createConfigurationByQName(location.getModule(), configurationContext, containingClass.getFQName());
+            return createConfigurationByQName(location.getModule(), configurationContext, getFQName(containingClass));
         }
         PsiFile psiFile = location.getPsiElement().getContainingFile();
         if (psiFile instanceof JetFile) {