[java] Preserve comments in convert to varargs method fix

#IDEA-376822 Fixed

GitOrigin-RevId: 9e1340bd15e54e3a2f3fda1017ce11aa2433cba2

java/java-analysis-impl/src/com/siyeh/ig/fixes/ConvertToVarargsMethodFix.java

@@ -7,6 +7,7 @@ import com.intellij.openapi.project.Project;
 import com.intellij.psi.*;
 import com.intellij.psi.search.searches.ReferencesSearch;
 import com.siyeh.InspectionGadgetsBundle;
+import com.siyeh.ig.psiutils.CommentTracker;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.ArrayList;
@@ -56,7 +57,10 @@ public class ConvertToVarargsMethodFix extends PsiUpdateModCommandQuickFix {
     final PsiTypeElement newTypeElement = factory.createTypeElement(ellipsisType);
     final PsiTypeElement typeElement = lastParameter.getTypeElement();
     if (typeElement != null) {
-      typeElement.replace(newTypeElement);
+      CommentTracker ct = new CommentTracker();
+      ct.grabComments(typeElement);
+      PsiElement result = typeElement.replace(newTypeElement);
+      ct.insertCommentsBefore(result.getLastChild()); // Swap comments, example: String /* Foo */ [] -> String/* Foo */...
     }
   }
 

java/java-tests/testData/ig/com/siyeh/igfixes/migration/convert_to_varargs_method/Comment.after.java

@@ -0,0 +1,4 @@
+class Test {
+  public void foo(/* Before */ String/* Middle */... a<caret>rg) {
+  }
+}

java/java-tests/testData/ig/com/siyeh/igfixes/migration/convert_to_varargs_method/Comment.java

@@ -0,0 +1,4 @@
+class Test {
+  public void foo(/* Before */ String /* Middle */ [] a<caret>rg) {
+  }
+}

java/java-tests/testSrc/com/siyeh/ig/fixes/migration/ConvertToVarargsMethodFixTest.java

@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2016 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.siyeh.ig.fixes.migration;
 
 import com.siyeh.InspectionGadgetsBundle;
@@ -25,6 +11,7 @@ import com.siyeh.ig.migration.MethodCanBeVariableArityMethodInspection;
 public class ConvertToVarargsMethodFixTest extends IGQuickFixesTestCase {
 
   public void testDeepArray() { doTest(); }
+  public void testComment() { doTest(); }
   public void testFinal() { doTest(); }
   public void testCStyle() { doTest(); }