ConvertSwitchToIfIntention: preserve comments from expression when only default branch is present

java/java-impl/src/com/intellij/codeInsight/daemon/impl/quickfix/ConvertSwitchToIfIntention.java

@@ -91,7 +91,6 @@ public class ConvertSwitchToIfIntention implements IntentionAction {
       return;
     }
     CommentTracker commentTracker = new CommentTracker();
-    commentTracker.markUnchanged(switchExpression);
     final boolean isSwitchOnString = switchExpressionType.equalsToText(CommonClassNames.JAVA_LANG_STRING);
     boolean useEquals = isSwitchOnString;
     if (!useEquals) {
@@ -114,8 +113,11 @@ public class ConvertSwitchToIfIntention implements IntentionAction {
     final boolean hadSideEffects;
     final String expressionText;
     final Project project = switchStatement.getProject();
-    if (allBranches.stream().mapToInt(br -> br.getCaseValues().size()).sum() > 1 &&
-        RemoveUnusedVariableUtil.checkSideEffects(switchExpression, null, new ArrayList<>())) {
+    int totalCases = allBranches.stream().mapToInt(br -> br.getCaseValues().size()).sum();
+    if (totalCases > 0) {
+      commentTracker.markUnchanged(switchExpression);
+    }
+    if (totalCases > 1 && RemoveUnusedVariableUtil.checkSideEffects(switchExpression, null, new ArrayList<>())) {
       hadSideEffects = true;
 
       final String variableName = new VariableNameGenerator(switchExpression, VariableKind.LOCAL_VARIABLE)

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/switchDefault/afterBreakLast.java

@@ -1,6 +1,7 @@
 // "Unwrap 'switch'" "true"
 class X {
   String test(char c) {
+      /*comment*/
       if (c == 'a') {
           System.out.println("foo");
       }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/switchDefault/beforeBreakLast.java

@@ -1,7 +1,7 @@
 // "Unwrap 'switch'" "true"
 class X {
   String test(char c) {
-    s<caret>witch (c) {
+    s<caret>witch (c/*comment*/) {
       default:
         if(c == 'a') {
           System.out.println("foo");