Move: Do not add package directive if target package is empty

#KT-6455 Fixed

idea/src/org/jetbrains/jet/plugin/refactoring/jetRefactoringUtil.kt

@@ -89,7 +89,7 @@ fun createKotlinFile(fileName: String, targetDir: PsiDirectory): JetFile {
 
     targetDir.checkCreateFile(fileName)
     val file = PsiFileFactory.getInstance(targetDir.getProject()).createFileFromText(
-            fileName, JetFileType.INSTANCE, if (packageName != null) "package $packageName \n\n" else ""
+            fileName, JetFileType.INSTANCE, if (packageName != null && packageName.isNotEmpty()) "package $packageName \n\n" else ""
     )
 
     return targetDir.add(file) as JetFile

idea/testData/refactoring/move/kotlin/moveTopLevelDeclarations/misc/moveClassToDefaultPackage/after/X.kt

@@ -0,0 +1,3 @@
+class X {
+
+}

idea/testData/refactoring/move/kotlin/moveTopLevelDeclarations/misc/moveClassToDefaultPackage/after/a/main.kt

@@ -0,0 +1,5 @@
+package a
+
+class Y {
+
+}

idea/testData/refactoring/move/kotlin/moveTopLevelDeclarations/misc/moveClassToDefaultPackage/before/a/main.kt

@@ -0,0 +1,9 @@
+package a
+
+class <caret>X {
+
+}
+
+class Y {
+
+}

idea/testData/refactoring/move/kotlin/moveTopLevelDeclarations/misc/moveClassToDefaultPackage/moveClassToDefaultPackage.test

@@ -0,0 +1,5 @@
+{
+  "mainFile": "a/main.kt",
+  "type": "MOVE_KOTLIN_TOP_LEVEL_DECLARATIONS",
+  "targetPackage": ""
+}

idea/tests/org/jetbrains/jet/plugin/refactoring/move/JetMoveTestGenerated.java

@@ -246,6 +246,12 @@ public class JetMoveTestGenerated extends AbstractJetMoveTest {
         doTest(fileName);
     }
 
+    @TestMetadata("kotlin/moveTopLevelDeclarations/misc/moveClassToDefaultPackage/moveClassToDefaultPackage.test")
+    public void testKotlin_moveTopLevelDeclarations_misc_moveClassToDefaultPackage_MoveClassToDefaultPackage() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("idea/testData/refactoring/move/kotlin/moveTopLevelDeclarations/misc/moveClassToDefaultPackage/moveClassToDefaultPackage.test");
+        doTest(fileName);
+    }
+
     @TestMetadata("kotlin/moveTopLevelDeclarations/misc/moveClassWithImportsRetained/moveClassWithImportsRetained.test")
     public void testKotlin_moveTopLevelDeclarations_misc_moveClassWithImportsRetained_MoveClassWithImportsRetained() throws Exception {
         String fileName = JetTestUtils.navigationMetadata("idea/testData/refactoring/move/kotlin/moveTopLevelDeclarations/misc/moveClassWithImportsRetained/moveClassWithImportsRetained.test");