<PackageReference Include="Newtonsoft.Json" Version="14.0.1-beta2" />

Newtonsoft.Json.Utilities.StringReference

namespace Newtonsoft.Json.Utilities { internal readonly struct StringReference { public char this[int i] { get; } public char[] Chars { get; } public int StartIndex { get; } public int Length { get; } public StringReference(char[] chars, int startIndex, int length); } }