A System.Text.Json converter implementation that efficiently encodes the BigInteger to Base64

BigIntegerBase64JsonConverter.cs

internal sealed class BigIntegerBase64JsonConverter : JsonConverter<BigInteger>
{
    public override BigInteger Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        var bigIntegerBytes = reader.GetBytesFromBase64();

        return new BigInteger(bigIntegerBytes);
    }

    public override void Write(Utf8JsonWriter writer, BigInteger value, JsonSerializerOptions options)
    {
        var bytes = ArrayPool<byte>.Shared.Rent(value.GetByteCount());

        try
        {
            value.TryWriteBytes(bytes, out _);

            writer.WriteBase64StringValue(bytes);
        }
        finally
        {
            ArrayPool<byte>.Shared.Return(bytes);
        }
    }
}