invert if: ensure outer if becomes braces when nested if has no else brunch (IDEA-206882)

java/java-impl/src/com/intellij/codeInsight/intention/impl/InvertIfConditionAction.java

@@ -142,7 +142,11 @@ public class InvertIfConditionAction extends PsiElementBaseIntentionAction {
         elseBranch = Objects.requireNonNull(ifStatement.getElseBranch()).replace(elseBranch);
 
         if (emptyBlock(((PsiBlockStatement)elseBranch).getCodeBlock())) {
-          new CommentTracker().deleteAndRestoreComments(ifStatement.getElseBranch());
+          PsiElement parent = ifStatement.getParent();
+          if (parent instanceof PsiIfStatement && ((PsiIfStatement)parent).getElseBranch() != null) {
+            ifStatement = (PsiIfStatement)wrapWithCodeBlock(ifStatement);
+          }
+          new CommentTracker().deleteAndRestoreComments(Objects.requireNonNull(ifStatement.getElseBranch()));
         }
       }
     }

java/java-tests/testData/codeInsight/invertIfCondition/afterNestedIf6.java

@@ -0,0 +1,13 @@
+// "Invert 'if' condition" "true"
+class Main {
+    void foo(boolean a1, boolean b1){
+        if (a1) {
+            if (!b1) {
+                System.out.println("1");
+            }
+        }
+        else {
+            System.out.println("2");
+        }
+    }
+}

java/java-tests/testData/codeInsight/invertIfCondition/beforeNestedIf6.java

@@ -0,0 +1,13 @@
+// "Invert 'if' condition" "true"
+class Main {
+    void foo(boolean a1, boolean b1){
+        if (a1)
+            if (b<caret>1) {
+            } else {
+                System.out.println("1");
+            }
+        else {
+            System.out.println("2");
+        }
+    }
+}