BsonRegex
namespace Newtonsoft.Json.Bson
{
    internal class BsonRegex : BsonToken
    {
        public BsonString Pattern { get; set; }
        public BsonString Options { get; set; }
        public override BsonType Type => BsonType.Regex;
        public BsonRegex(string pattern, string options)
        {
            Pattern = new BsonString(pattern, false);
            Options = new BsonString(options, false);
        }
    }
}