anchor.diff:    Classifier bound;
   
     TypeParameterBuilder._();
  +
     factory TypeParameterBuilder() = _$TypeParameterBuilder;
   }
   
   abstract class Property
       implements Built<Property, PropertyBuilder>, NamedElement {
     static final Serializer<Property> serializer = _$propertySerializer;
  +
     String get name;
     Classifier get type;
     bool get isNullable;
     @nullable
     Object get defaultValue;
  -
     @nullable
     String get derivedExpression;
  -
     bool get isDerived => derivedExpression != null;
   
     Property._();
  
positive.code: abstract class GenericType
      implements Built<GenericType, GenericTypeBuilder>, Classifier {
    static final Serializer<GenericType> serializer = _$genericTypeSerializer;
    String get name;
    Classifier get base;
    BuiltMap<TypeParameter, Classifier> get genericTypeValues;
  
negative.code: abstract class ExternalClassBuilder
      implements Builder<ExternalClass, ExternalClassBuilder> {
    String name;
    SetBuilder<TypeParameter> genericTypes = new SetBuilder<TypeParameter>();
  
    ExternalClassBuilder._();
  
    factory ExternalClassBuilder() = _$ExternalClassBuilder;
  }
  
  abstract class Package implements Built<Package, PackageBuilder>, NamedElement {
    static final Serializer<Package> serializer = _$packageSerializer;
  
    String get name;
    BuiltSet<Classifier> get classifiers;
  
  