@Override
 public void visitLiteralExpression(@NotNull PsiLiteralExpression value) {
   super.visitLiteralExpression(value);
   final String text = value.getText();
   if (!PsiKeyword.NULL.equals(text)) {
     return;
   }
   PsiElement parent = value.getParent();
   while (parent instanceof PsiParenthesizedExpression
       || parent instanceof PsiConditionalExpression
       || parent instanceof PsiTypeCastExpression) {
     parent = parent.getParent();
   }
   if (parent == null || !(parent instanceof PsiReturnStatement)) {
     return;
   }
   final PsiMethod method = PsiTreeUtil.getParentOfType(value, PsiMethod.class);
   if (method == null) {
     return;
   }
   final PsiType returnType = method.getReturnType();
   if (returnType == null) {
     return;
   }
   final boolean isArray = returnType.getArrayDimensions() > 0;
   if (AnnotationUtil.isAnnotated(method, AnnotationUtil.NULLABLE, false)) {
     return;
   }
   if (m_reportCollectionMethods && CollectionUtils.isCollectionClassOrInterface(returnType)) {
     registerError(value, value);
   } else if (m_reportArrayMethods && isArray) {
     registerError(value, value);
   } else if (m_reportObjectMethods && !isArray) {
     registerError(value, value);
   }
 }
 private boolean checkCondition(
     @Nullable PsiExpression condition,
     @NotNull PsiStatement context,
     List<PsiExpression> notUpdated) {
   if (condition == null) {
     return false;
   }
   if (PsiUtil.isConstantExpression(condition) || PsiKeyword.NULL.equals(condition.getText())) {
     return true;
   }
   if (condition instanceof PsiInstanceOfExpression) {
     final PsiInstanceOfExpression instanceOfExpression = (PsiInstanceOfExpression) condition;
     final PsiExpression operand = instanceOfExpression.getOperand();
     return checkCondition(operand, context, notUpdated);
   } else if (condition instanceof PsiParenthesizedExpression) {
     // catch stuff like "while ((x)) { ... }"
     final PsiExpression expression = ((PsiParenthesizedExpression) condition).getExpression();
     return checkCondition(expression, context, notUpdated);
   } else if (condition instanceof PsiPolyadicExpression) {
     // while (value != x) { ... }
     // while (value != (x + y)) { ... }
     // while (b1 && b2) { ... }
     final PsiPolyadicExpression polyadicExpression = (PsiPolyadicExpression) condition;
     for (PsiExpression operand : polyadicExpression.getOperands()) {
       if (!checkCondition(operand, context, notUpdated)) {
         return false;
       }
     }
     return true;
   } else if (condition instanceof PsiReferenceExpression) {
     final PsiReferenceExpression referenceExpression = (PsiReferenceExpression) condition;
     final PsiElement element = referenceExpression.resolve();
     if (element instanceof PsiField) {
       final PsiField field = (PsiField) element;
       final PsiType type = field.getType();
       if (field.hasModifierProperty(PsiModifier.FINAL) && type.getArrayDimensions() == 0) {
         if (field.hasModifierProperty(PsiModifier.STATIC)) {
           return true;
         }
         final PsiExpression qualifier = referenceExpression.getQualifierExpression();
         if (qualifier == null) {
           return true;
         } else if (checkCondition(qualifier, context, notUpdated)) {
           return true;
         }
       }
     } else if (element instanceof PsiVariable) {
       final PsiVariable variable = (PsiVariable) element;
       if (variable.hasModifierProperty(PsiModifier.FINAL)) {
         // final variables cannot be updated, don't bother to
         // flag them
         return true;
       } else if (element instanceof PsiLocalVariable || element instanceof PsiParameter) {
         if (!VariableAccessUtils.variableIsAssigned(variable, context)) {
           notUpdated.add(referenceExpression);
           return true;
         }
       }
     }
   } else if (condition instanceof PsiPrefixExpression) {
     final PsiPrefixExpression prefixExpression = (PsiPrefixExpression) condition;
     final IElementType tokenType = prefixExpression.getOperationTokenType();
     if (JavaTokenType.EXCL.equals(tokenType)
         || JavaTokenType.PLUS.equals(tokenType)
         || JavaTokenType.MINUS.equals(tokenType)) {
       final PsiExpression operand = prefixExpression.getOperand();
       return checkCondition(operand, context, notUpdated);
     }
   } else if (condition instanceof PsiArrayAccessExpression) {
     // Actually the contents of the array could change nevertheless
     // if it is accessed through a different reference like this:
     //   int[] local_ints = new int[]{1, 2};
     //   int[] other_ints = local_ints;
     //   while (local_ints[0] > 0) { other_ints[0]--; }
     //
     // Keep this check?
     final PsiArrayAccessExpression accessExpression = (PsiArrayAccessExpression) condition;
     final PsiExpression indexExpression = accessExpression.getIndexExpression();
     return checkCondition(indexExpression, context, notUpdated)
         && checkCondition(accessExpression.getArrayExpression(), context, notUpdated);
   } else if (condition instanceof PsiConditionalExpression) {
     final PsiConditionalExpression conditionalExpression = (PsiConditionalExpression) condition;
     final PsiExpression thenExpression = conditionalExpression.getThenExpression();
     final PsiExpression elseExpression = conditionalExpression.getElseExpression();
     if (thenExpression == null || elseExpression == null) {
       return false;
     }
     return checkCondition(conditionalExpression.getCondition(), context, notUpdated)
         && checkCondition(thenExpression, context, notUpdated)
         && checkCondition(elseExpression, context, notUpdated);
   } else if (condition instanceof PsiThisExpression) {
     return true;
   } else if (condition instanceof PsiMethodCallExpression && !ignoreIterators) {
     final PsiMethodCallExpression methodCallExpression = (PsiMethodCallExpression) condition;
     if (!IteratorUtils.isCallToHasNext(methodCallExpression)) {
       return false;
     }
     final PsiReferenceExpression methodExpression = methodCallExpression.getMethodExpression();
     final PsiExpression qualifierExpression = methodExpression.getQualifierExpression();
     if (qualifierExpression instanceof PsiReferenceExpression) {
       final PsiReferenceExpression referenceExpression =
           (PsiReferenceExpression) qualifierExpression;
       final PsiElement element = referenceExpression.resolve();
       if (!(element instanceof PsiVariable)) {
         return false;
       }
       final PsiVariable variable = (PsiVariable) element;
       if (!IteratorUtils.containsCallToScannerNext(context, variable, true)) {
         notUpdated.add(qualifierExpression);
         return true;
       }
     } else {
       if (!IteratorUtils.containsCallToScannerNext(context, null, true)) {
         notUpdated.add(methodCallExpression);
         return true;
       }
     }
   }
   return false;
 }