using System.Runtime.CompilerServices; namespace System.Text.Json.Serialization { [System.Runtime.CompilerServices.NullableContext(1)] [System.Runtime.CompilerServices.Nullable(0)] public abstract class ReferenceResolver { public abstract void AddReference(string referenceId, object value); public abstract string GetReference(object value, out bool alreadyExists); public abstract object ResolveReference(string referenceId); } }