anchor.diff:          bool fieldInConstructor(constructor) =>
               constructor.initializers.any((initializer) =>
                   _containedInInitializer(element, initializer)) ||
  -                constructor.parameters.parameters
  -                    .any((formal) => _containedInFormal(element, formal));
  +            constructor.parameters.parameters
  +                .any((formal) => _containedInFormal(element, formal));
   
           final classDeclaration = node.parent;
           final constructors = (classDeclaration is ClassDeclaration
               ? classDeclaration.members
  -            .whereType<ConstructorDeclaration>()
  -            .toSet()
  +                .whereType<ConstructorDeclaration>()
  +                .toSet()
               : <ConstructorDeclaration>{});
           final isFieldInConstructors = constructors.any(fieldInConstructor);
           final isFieldInAllConstructors = constructors.every(fieldInConstructor);
  
positive.code: }
  
  bool _containedInInitializer(
      Element element, ConstructorInitializer initializer) =>
      initializer is ConstructorFieldInitializer &&
          DartTypeUtilities.getCanonicalElementFromIdentifier(
              initializer.fieldName) ==
              element;
  
  bool _containedInFormal(Element element, FormalParameter formal) =>
      formal is FieldFormalParameter &&
          formal.declaredElement.toString() == element.toString();
  
negative.code: 
    void _addMutatedFieldElement(Expression expression) {
      final element =
          DartTypeUtilities.getCanonicalElementFromIdentifier(expression);
      if (element is FieldElement) {
        _mutatedFields.add(element);
      }
  