Fix replace with computeIfAbsent when resulting var is not used (see also IDEA-166625)

java/java-impl/src/com/intellij/codeInspection/java18api/Java8MapApiInspection.java

@@ -464,7 +464,7 @@ public class Java8MapApiInspection extends BaseJavaBatchLocalInspectionTool {
         ct.deleteAndRestoreComments(conditional);
       }
       PsiVariable variable = condition.extractDeclaration();
-      if(variable != null && ReferencesSearch.search(variable).findFirst() == null) {
+      if (variable != null && !PsiTreeUtil.isAncestor(result, variable, true) && ReferencesSearch.search(variable).findFirst() == null) {
         new CommentTracker().deleteAndRestoreComments(variable);
       }
       CodeStyleManager.getInstance(project).reformat(result);

java/java-tests/testData/inspection/java8MapApi/afterComputeIfAbsentResultUnused.java

@@ -0,0 +1,11 @@
+// "Replace with 'computeIfAbsent' method call" "true"
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+public class Test {
+    interface Shift {}
+    void foo(Map<String, List<Shift>> dayOfWeekAndShiftTypeToShiftListMap, String key){
+        List<Shift> dayOfWeekAndShiftTypeToShiftList = dayOfWeekAndShiftTypeToShiftListMap.computeIfAbsent(key, k -> new ArrayList<>((6) / 7));
+    }
+}

java/java-tests/testData/inspection/java8MapApi/beforeComputeIfAbsentResultUnused.java

@@ -0,0 +1,15 @@
+// "Replace with 'computeIfAbsent' method call" "true"
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+public class Test {
+    interface Shift {}
+    void foo(Map<String, List<Shift>> dayOfWeekAndShiftTypeToShiftListMap, String key){
+        List<Shift> dayOfWeekAndShiftTypeToShiftList = dayOfWeekAndShiftTypeToShiftListMap.get(key);
+        if (<caret>dayOfWeekAndShiftTypeToShiftList == null) {
+            dayOfWeekAndShiftTypeToShiftList = new ArrayList<>((6) / 7);
+            dayOfWeekAndShiftTypeToShiftListMap.put(key, dayOfWeekAndShiftTypeToShiftList);
+        }
+    }
+}