diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/TrackingRunner.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/TrackingRunner.java
index 89488bb17f4f..26f640ccacab 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/TrackingRunner.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/TrackingRunner.java
@@ -106,18 +106,19 @@ public class TrackingRunner extends StandardDataFlowRunner {
     return states;
   }
 
-  public static List<CauseItem> findProblemCause(boolean unknownAreNullables,
-                                                 boolean ignoreAssertions,
-                                                 PsiExpression expression,
-                                                 DfaProblemType type) {
+  @Nullable
+  public static CauseItem findProblemCause(boolean unknownAreNullables,
+                                           boolean ignoreAssertions,
+                                           PsiExpression expression,
+                                           DfaProblemType type) {
     PsiElement body = DfaUtil.getDataflowContext(expression);
-    if (body == null) return Collections.emptyList();
+    if (body == null) return null;
     TrackingRunner runner = new TrackingRunner(unknownAreNullables, body, expression);
-    if (!analyze(ignoreAssertions, expression, body, runner)) return Collections.emptyList();
-    return ContainerUtil.createMaybeSingletonList(runner.findProblemCause(expression, type));
+    if (!runner.analyze(ignoreAssertions, expression, body)) return null;
+    return runner.findProblemCause(expression, type);
   }
 
-  private static boolean analyze(boolean ignoreAssertions, PsiExpression expression, PsiElement body, TrackingRunner runner) {
+  private boolean analyze(boolean ignoreAssertions, PsiExpression expression, PsiElement body) {
     List<DfaMemoryState> endOfInitializerStates = new ArrayList<>();
     StandardInstructionVisitor visitor = new StandardInstructionVisitor(true) {
       @Override
@@ -130,7 +131,7 @@ public class TrackingRunner extends StandardDataFlowRunner {
         return super.visitEndOfInitializer(instruction, runner, state);
       }
     };
-    RunnerResult result = runner.analyzeMethodRecursively(body, visitor, ignoreAssertions);
+    RunnerResult result = analyzeMethodRecursively(body, visitor, ignoreAssertions);
     if (result != RunnerResult.OK) return false;
     if (body instanceof PsiClass) {
       PsiMethod ctor = PsiTreeUtil.getParentOfType(expression, PsiMethod.class, true, PsiClass.class, PsiLambdaExpression.class);
@@ -141,12 +142,12 @@ public class TrackingRunner extends StandardDataFlowRunner {
           PsiMethodCallExpression call = JavaPsiConstructorUtil.findThisOrSuperCallInConstructor(ctor);
           if (JavaPsiConstructorUtil.isChainedConstructorCall(call) ||
               (call == null && hasImplicitImpureSuperCall((PsiClass)body, ctor))) {
-            initialStates = Collections.singletonList(runner.createMemoryState());
+            initialStates = Collections.singletonList(createMemoryState());
           }
           else {
             initialStates = StreamEx.of(endOfInitializerStates).map(DfaMemoryState::createCopy).toList();
           }
-          return runner.analyzeBlockRecursively(ctorBody, initialStates, visitor, false) == RunnerResult.OK;
+          return analyzeBlockRecursively(ctorBody, initialStates, visitor, false) == RunnerResult.OK;
         }
       }
     }
diff --git a/java/java-impl/src/com/intellij/codeInspection/dataFlow/fix/FindDfaProblemCauseFix.java b/java/java-impl/src/com/intellij/codeInspection/dataFlow/fix/FindDfaProblemCauseFix.java
index c8a185c6e684..2028048dcc51 100644
--- a/java/java-impl/src/com/intellij/codeInspection/dataFlow/fix/FindDfaProblemCauseFix.java
+++ b/java/java-impl/src/com/intellij/codeInspection/dataFlow/fix/FindDfaProblemCauseFix.java
@@ -69,27 +69,26 @@ public class FindDfaProblemCauseFix implements LocalQuickFix, LowPriorityAction
 
   @Override
   public void applyFix(@NotNull Project project, @NotNull ProblemDescriptor descriptor) {
-    ThrowableComputable<List<TrackingRunner.CauseItem>, RuntimeException> causeFinder = () -> {
+    ThrowableComputable<TrackingRunner.CauseItem, RuntimeException> causeFinder = () -> {
       PsiExpression element = myAnchor.getElement();
-      if (element == null) return Collections.emptyList();
+      if (element == null) return null;
       return TrackingRunner.findProblemCause(myUnknownMembersAsNullable, myIgnoreAssertStatements, element, myProblemType);
     };
-    List<TrackingRunner.CauseItem> items = ProgressManager.getInstance().runProcessWithProgressSynchronously(
+    TrackingRunner.CauseItem item = ProgressManager.getInstance().runProcessWithProgressSynchronously(
       () -> ReadAction.compute(causeFinder), "Finding Cause", true, project);
     PsiFile file = myAnchor.getContainingFile();
-    if (!items.isEmpty() && file != null) {
-      displayProblemCause(file, items);
+    if (item != null && file != null) {
+      displayProblemCause(file, item);
     }
   }
 
-  private static void displayProblemCause(PsiFile file, List<TrackingRunner.CauseItem> items) {
+  private static void displayProblemCause(PsiFile file, TrackingRunner.CauseItem root) {
     Project project = file.getProject();
     Editor editor = FileEditorManager.getInstance(project).getSelectedTextEditor();
     if (editor == null) return;
     Document document = editor.getDocument();
     PsiFile topLevelFile = InjectedLanguageManager.getInstance(project).getTopLevelFile(file);
     if (topLevelFile == null || document != topLevelFile.getViewProvider().getDocument()) return;
-    TrackingRunner.CauseItem root = ContainerUtil.getOnlyItem(items);
     class CauseWithDepth {
       final int myDepth;
       final TrackingRunner.CauseItem myCauseItem;