diff --git a/packages/mix/lib/src/specs/box/box_spec.dart b/packages/mix/lib/src/specs/box/box_spec.dart
index 6962cd4d0..93817edc3 100644
--- a/packages/mix/lib/src/specs/box/box_spec.dart
+++ b/packages/mix/lib/src/specs/box/box_spec.dart
@@ -4,8 +4,6 @@ import 'package:flutter/widgets.dart';
 import 'package:mix/mix.dart';
 import 'package:mix_annotations/mix_annotations.dart';
 
-import '../../internal/diagnostic_properties_builder_ext.dart';
-
 part 'box_spec.g.dart';
 
 const _constraints = MixableUtility(
diff --git a/packages/mix/lib/src/specs/box/box_spec.g.dart b/packages/mix/lib/src/specs/box/box_spec.g.dart
index 783151ea3..54d051a55 100644
--- a/packages/mix/lib/src/specs/box/box_spec.g.dart
+++ b/packages/mix/lib/src/specs/box/box_spec.g.dart
@@ -255,19 +255,29 @@ final class BoxSpecAttribute extends SpecAttribute<BoxSpec>
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
-    properties.addUsingDefault('alignment', alignment);
-    properties.addUsingDefault('padding', padding);
-    properties.addUsingDefault('margin', margin);
-    properties.addUsingDefault('constraints', constraints);
-    properties.addUsingDefault('decoration', decoration, expandableValue: true);
-    properties.addUsingDefault('foregroundDecoration', foregroundDecoration);
-    properties.addUsingDefault('transform', transform);
-    properties.addUsingDefault('transformAlignment', transformAlignment);
-    properties.addUsingDefault('clipBehavior', clipBehavior);
-    properties.addUsingDefault('width', width);
-    properties.addUsingDefault('height', height);
-    properties.addUsingDefault('modifiers', modifiers);
-    properties.addUsingDefault('animated', animated);
+    properties
+        .add(DiagnosticsProperty('alignment', alignment, defaultValue: null));
+    properties.add(DiagnosticsProperty('padding', padding, defaultValue: null));
+    properties.add(DiagnosticsProperty('margin', margin, defaultValue: null));
+    properties.add(
+        DiagnosticsProperty('constraints', constraints, defaultValue: null));
+    properties.add(DiagnosticsProperty('decoration', decoration,
+        expandableValue: true, defaultValue: null));
+    properties.add(DiagnosticsProperty(
+        'foregroundDecoration', foregroundDecoration,
+        defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('transform', transform, defaultValue: null));
+    properties.add(DiagnosticsProperty('transformAlignment', transformAlignment,
+        defaultValue: null));
+    properties.add(
+        DiagnosticsProperty('clipBehavior', clipBehavior, defaultValue: null));
+    properties.add(DiagnosticsProperty('width', width, defaultValue: null));
+    properties.add(DiagnosticsProperty('height', height, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('modifiers', modifiers, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('animated', animated, defaultValue: null));
   }
 }
 
diff --git a/packages/mix/lib/src/specs/flex/flex_spec.dart b/packages/mix/lib/src/specs/flex/flex_spec.dart
index 4f44eb68d..15e9cf53d 100644
--- a/packages/mix/lib/src/specs/flex/flex_spec.dart
+++ b/packages/mix/lib/src/specs/flex/flex_spec.dart
@@ -4,8 +4,6 @@ import 'package:flutter/widgets.dart';
 import 'package:mix/mix.dart';
 import 'package:mix_annotations/mix_annotations.dart';
 
-import '../../internal/diagnostic_properties_builder_ext.dart';
-
 part 'flex_spec.g.dart';
 
 @MixableSpec()
diff --git a/packages/mix/lib/src/specs/flex/flex_spec.g.dart b/packages/mix/lib/src/specs/flex/flex_spec.g.dart
index f6976492c..288ced1b5 100644
--- a/packages/mix/lib/src/specs/flex/flex_spec.g.dart
+++ b/packages/mix/lib/src/specs/flex/flex_spec.g.dart
@@ -232,17 +232,27 @@ final class FlexSpecAttribute extends SpecAttribute<FlexSpec>
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
-    properties.addUsingDefault('crossAxisAlignment', crossAxisAlignment);
-    properties.addUsingDefault('mainAxisAlignment', mainAxisAlignment);
-    properties.addUsingDefault('mainAxisSize', mainAxisSize);
-    properties.addUsingDefault('verticalDirection', verticalDirection);
-    properties.addUsingDefault('direction', direction);
-    properties.addUsingDefault('textDirection', textDirection);
-    properties.addUsingDefault('textBaseline', textBaseline);
-    properties.addUsingDefault('clipBehavior', clipBehavior);
-    properties.addUsingDefault('gap', gap);
-    properties.addUsingDefault('animated', animated);
-    properties.addUsingDefault('modifiers', modifiers);
+    properties.add(DiagnosticsProperty('crossAxisAlignment', crossAxisAlignment,
+        defaultValue: null));
+    properties.add(DiagnosticsProperty('mainAxisAlignment', mainAxisAlignment,
+        defaultValue: null));
+    properties.add(
+        DiagnosticsProperty('mainAxisSize', mainAxisSize, defaultValue: null));
+    properties.add(DiagnosticsProperty('verticalDirection', verticalDirection,
+        defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('direction', direction, defaultValue: null));
+    properties.add(DiagnosticsProperty('textDirection', textDirection,
+        defaultValue: null));
+    properties.add(
+        DiagnosticsProperty('textBaseline', textBaseline, defaultValue: null));
+    properties.add(
+        DiagnosticsProperty('clipBehavior', clipBehavior, defaultValue: null));
+    properties.add(DiagnosticsProperty('gap', gap, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('animated', animated, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('modifiers', modifiers, defaultValue: null));
   }
 }
 
diff --git a/packages/mix/lib/src/specs/icon/icon_spec.dart b/packages/mix/lib/src/specs/icon/icon_spec.dart
index b4b910e2d..d32862464 100644
--- a/packages/mix/lib/src/specs/icon/icon_spec.dart
+++ b/packages/mix/lib/src/specs/icon/icon_spec.dart
@@ -4,8 +4,6 @@ import 'package:flutter/widgets.dart';
 import 'package:mix/mix.dart';
 import 'package:mix_annotations/mix_annotations.dart';
 
-import '../../internal/diagnostic_properties_builder_ext.dart';
-
 part 'icon_spec.g.dart';
 
 @MixableSpec()
diff --git a/packages/mix/lib/src/specs/icon/icon_spec.g.dart b/packages/mix/lib/src/specs/icon/icon_spec.g.dart
index 4300ed7d4..a981da5a3 100644
--- a/packages/mix/lib/src/specs/icon/icon_spec.g.dart
+++ b/packages/mix/lib/src/specs/icon/icon_spec.g.dart
@@ -232,17 +232,22 @@ final class IconSpecAttribute extends SpecAttribute<IconSpec>
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
-    properties.addUsingDefault('color', color);
-    properties.addUsingDefault('size', size);
-    properties.addUsingDefault('weight', weight);
-    properties.addUsingDefault('grade', grade);
-    properties.addUsingDefault('opticalSize', opticalSize);
-    properties.addUsingDefault('shadows', shadows);
-    properties.addUsingDefault('textDirection', textDirection);
-    properties.addUsingDefault('applyTextScaling', applyTextScaling);
-    properties.addUsingDefault('fill', fill);
-    properties.addUsingDefault('animated', animated);
-    properties.addUsingDefault('modifiers', modifiers);
+    properties.add(DiagnosticsProperty('color', color, defaultValue: null));
+    properties.add(DiagnosticsProperty('size', size, defaultValue: null));
+    properties.add(DiagnosticsProperty('weight', weight, defaultValue: null));
+    properties.add(DiagnosticsProperty('grade', grade, defaultValue: null));
+    properties.add(
+        DiagnosticsProperty('opticalSize', opticalSize, defaultValue: null));
+    properties.add(DiagnosticsProperty('shadows', shadows, defaultValue: null));
+    properties.add(DiagnosticsProperty('textDirection', textDirection,
+        defaultValue: null));
+    properties.add(DiagnosticsProperty('applyTextScaling', applyTextScaling,
+        defaultValue: null));
+    properties.add(DiagnosticsProperty('fill', fill, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('animated', animated, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('modifiers', modifiers, defaultValue: null));
   }
 }
 
diff --git a/packages/mix/lib/src/specs/image/image_spec.dart b/packages/mix/lib/src/specs/image/image_spec.dart
index fc466e8ba..895992dba 100644
--- a/packages/mix/lib/src/specs/image/image_spec.dart
+++ b/packages/mix/lib/src/specs/image/image_spec.dart
@@ -4,8 +4,6 @@ import 'package:flutter/widgets.dart';
 import 'package:mix/mix.dart';
 import 'package:mix_annotations/mix_annotations.dart';
 
-import '../../internal/diagnostic_properties_builder_ext.dart';
-
 part 'image_spec.g.dart';
 
 @MixableSpec()
diff --git a/packages/mix/lib/src/specs/image/image_spec.g.dart b/packages/mix/lib/src/specs/image/image_spec.g.dart
index e3a0d4bfe..81a5e8f42 100644
--- a/packages/mix/lib/src/specs/image/image_spec.g.dart
+++ b/packages/mix/lib/src/specs/image/image_spec.g.dart
@@ -232,17 +232,23 @@ final class ImageSpecAttribute extends SpecAttribute<ImageSpec>
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
-    properties.addUsingDefault('width', width);
-    properties.addUsingDefault('height', height);
-    properties.addUsingDefault('color', color);
-    properties.addUsingDefault('repeat', repeat);
-    properties.addUsingDefault('fit', fit);
-    properties.addUsingDefault('alignment', alignment);
-    properties.addUsingDefault('centerSlice', centerSlice);
-    properties.addUsingDefault('filterQuality', filterQuality);
-    properties.addUsingDefault('colorBlendMode', colorBlendMode);
-    properties.addUsingDefault('animated', animated);
-    properties.addUsingDefault('modifiers', modifiers);
+    properties.add(DiagnosticsProperty('width', width, defaultValue: null));
+    properties.add(DiagnosticsProperty('height', height, defaultValue: null));
+    properties.add(DiagnosticsProperty('color', color, defaultValue: null));
+    properties.add(DiagnosticsProperty('repeat', repeat, defaultValue: null));
+    properties.add(DiagnosticsProperty('fit', fit, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('alignment', alignment, defaultValue: null));
+    properties.add(
+        DiagnosticsProperty('centerSlice', centerSlice, defaultValue: null));
+    properties.add(DiagnosticsProperty('filterQuality', filterQuality,
+        defaultValue: null));
+    properties.add(DiagnosticsProperty('colorBlendMode', colorBlendMode,
+        defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('animated', animated, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('modifiers', modifiers, defaultValue: null));
   }
 }
 
diff --git a/packages/mix/lib/src/specs/stack/stack_spec.dart b/packages/mix/lib/src/specs/stack/stack_spec.dart
index 9c7161a89..bc5702335 100644
--- a/packages/mix/lib/src/specs/stack/stack_spec.dart
+++ b/packages/mix/lib/src/specs/stack/stack_spec.dart
@@ -4,8 +4,6 @@ import 'package:flutter/widgets.dart';
 import 'package:mix/mix.dart';
 import 'package:mix_annotations/mix_annotations.dart';
 
-import '../../internal/diagnostic_properties_builder_ext.dart';
-
 part 'stack_spec.g.dart';
 
 @MixableSpec()
diff --git a/packages/mix/lib/src/specs/stack/stack_spec.g.dart b/packages/mix/lib/src/specs/stack/stack_spec.g.dart
index 37d5a7bb8..1e9b01846 100644
--- a/packages/mix/lib/src/specs/stack/stack_spec.g.dart
+++ b/packages/mix/lib/src/specs/stack/stack_spec.g.dart
@@ -184,12 +184,17 @@ final class StackSpecAttribute extends SpecAttribute<StackSpec>
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
-    properties.addUsingDefault('alignment', alignment);
-    properties.addUsingDefault('fit', fit);
-    properties.addUsingDefault('textDirection', textDirection);
-    properties.addUsingDefault('clipBehavior', clipBehavior);
-    properties.addUsingDefault('animated', animated);
-    properties.addUsingDefault('modifiers', modifiers);
+    properties
+        .add(DiagnosticsProperty('alignment', alignment, defaultValue: null));
+    properties.add(DiagnosticsProperty('fit', fit, defaultValue: null));
+    properties.add(DiagnosticsProperty('textDirection', textDirection,
+        defaultValue: null));
+    properties.add(
+        DiagnosticsProperty('clipBehavior', clipBehavior, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('animated', animated, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('modifiers', modifiers, defaultValue: null));
   }
 }
 
diff --git a/packages/mix/lib/src/specs/text/text_spec.dart b/packages/mix/lib/src/specs/text/text_spec.dart
index 11435a581..eccc63c9b 100644
--- a/packages/mix/lib/src/specs/text/text_spec.dart
+++ b/packages/mix/lib/src/specs/text/text_spec.dart
@@ -4,8 +4,6 @@ import 'package:flutter/widgets.dart';
 import 'package:mix/mix.dart';
 import 'package:mix_annotations/mix_annotations.dart';
 
-import '../../internal/diagnostic_properties_builder_ext.dart';
-
 part 'text_spec.g.dart';
 
 @MixableSpec()
diff --git a/packages/mix/lib/src/specs/text/text_spec.g.dart b/packages/mix/lib/src/specs/text/text_spec.g.dart
index 740e65862..00c23ca82 100644
--- a/packages/mix/lib/src/specs/text/text_spec.g.dart
+++ b/packages/mix/lib/src/specs/text/text_spec.g.dart
@@ -261,20 +261,34 @@ final class TextSpecAttribute extends SpecAttribute<TextSpec>
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
-    properties.addUsingDefault('overflow', overflow);
-    properties.addUsingDefault('strutStyle', strutStyle);
-    properties.addUsingDefault('textAlign', textAlign);
-    properties.addUsingDefault('textScaleFactor', textScaleFactor);
-    properties.addUsingDefault('textScaler', textScaler);
-    properties.addUsingDefault('maxLines', maxLines);
-    properties.addUsingDefault('style', style, expandableValue: true);
-    properties.addUsingDefault('textWidthBasis', textWidthBasis);
-    properties.addUsingDefault('textHeightBehavior', textHeightBehavior);
-    properties.addUsingDefault('textDirection', textDirection);
-    properties.addUsingDefault('softWrap', softWrap);
-    properties.addUsingDefault('directive', directive);
-    properties.addUsingDefault('animated', animated);
-    properties.addUsingDefault('modifiers', modifiers);
+    properties
+        .add(DiagnosticsProperty('overflow', overflow, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('strutStyle', strutStyle, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('textAlign', textAlign, defaultValue: null));
+    properties.add(DiagnosticsProperty('textScaleFactor', textScaleFactor,
+        defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('textScaler', textScaler, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('maxLines', maxLines, defaultValue: null));
+    properties.add(DiagnosticsProperty('style', style,
+        expandableValue: true, defaultValue: null));
+    properties.add(DiagnosticsProperty('textWidthBasis', textWidthBasis,
+        defaultValue: null));
+    properties.add(DiagnosticsProperty('textHeightBehavior', textHeightBehavior,
+        defaultValue: null));
+    properties.add(DiagnosticsProperty('textDirection', textDirection,
+        defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('softWrap', softWrap, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('directive', directive, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('animated', animated, defaultValue: null));
+    properties
+        .add(DiagnosticsProperty('modifiers', modifiers, defaultValue: null));
   }
 }
 
diff --git a/packages/mix/pubspec.yaml b/packages/mix/pubspec.yaml
index bcc0635c5..fe6aebe53 100644
--- a/packages/mix/pubspec.yaml
+++ b/packages/mix/pubspec.yaml
@@ -13,7 +13,7 @@ dependencies:
     sdk: flutter
 
 dev_dependencies:
-  flutter_lints: ^3.0.1
+  flutter_lints: ^4.0.0
   flutter_test:
     sdk: flutter
   dart_code_metrics_presets: ^2.13.0
diff --git a/packages/mix_generator/lib/src/builders/method_debug_fill_properties.dart b/packages/mix_generator/lib/src/builders/method_debug_fill_properties.dart
index 20e6aab74..11565a1ad 100644
--- a/packages/mix_generator/lib/src/builders/method_debug_fill_properties.dart
+++ b/packages/mix_generator/lib/src/builders/method_debug_fill_properties.dart
@@ -10,9 +10,9 @@ String methodDebugFillProperties({
   final fieldStatements = fields.map((field) {
     final fieldName = isInternalRef ? field.asInternalRef : field.name;
     if (_expandableFields.contains(fieldName)) {
-      return 'properties.add(DiagnosticsProperty(\'$fieldName\', $fieldName, expandableValue: true));';
+      return 'properties.add(DiagnosticsProperty(\'$fieldName\', $fieldName, expandableValue: true, defaultValue: null));';
     }
-    return 'properties.add(DiagnosticsProperty(\'$fieldName\', $fieldName));';
+    return 'properties.add(DiagnosticsProperty(\'$fieldName\', $fieldName, defaultValue: null));';
   }).join('\n');
 
   return '''
diff --git a/packages/mix_generator/lib/src/builders/method_merge.dart b/packages/mix_generator/lib/src/builders/method_merge.dart
index b624b7760..ac79fff44 100644
--- a/packages/mix_generator/lib/src/builders/method_merge.dart
+++ b/packages/mix_generator/lib/src/builders/method_merge.dart
@@ -50,7 +50,7 @@ String mergeMethodBuilder({
 
       return '$propAssignment $thisName$nullable.merge(other.$propName) ?? other.$propName';
     } else {
-      return '$propAssignment other$nullable.$propName ?? $thisName';
+      return '$propAssignment other.$propName ?? $thisName';
     }
   }).join(',\n      ');