anchor.diff:        new GraphQLNonNullableType<Value, Serialized>._(this);
   }
   
  +/// A special [GraphQLType] that indicates that input values should both be non-null, and be valid when asserted against another type, named [ofType].
   class GraphQLNonNullableType<Value, Serialized>
       extends GraphQLType<Value, Serialized> {
     final GraphQLType<Value, Serialized> ofType;
  
positive.code: part of graphql_schema.src.schema;
  
  abstract class GraphQLType<Value, Serialized> {
    String get name;
  
    String get description;
  
    Serialized serialize(Value value);
  
    Value deserialize(Serialized serialized);
  
    ValidationResult<Serialized> validate(String key, Serialized input);
  
    GraphQLType<Value, Serialized> nonNullable();
  
    GraphQLType<Value, Serialized> coerceToInputObject();
  
    @override
  
negative.code:         GraphQLType<Value, Serialized> innerType) =>
      new GraphQLListType<Value, Serialized>(innerType);
  
  /// A special [GraphQLType] that indicates that input vales should be a list of another type, [ofType].
  class GraphQLListType<Value, Serialized>
      extends GraphQLType<List<Value>, List<Serialized>>
      with _NonNullableMixin<List<Value>, List<Serialized>> {
  