Update RestSharp to v107 and follow recommended usage

[sebastian-sawicki]

With the new version implemented, RestSharp solves a couple of issues:

• Socket exhaustion
• Hanging connections
• SimpleJson serialization issues
• HTTP/2 support

Upgrade RestSharp to to v107 https://restsharp.dev/v107/#restsharp-v107
and follow best practices https://restsharp.dev/v107/#recommended-usage

https://code-maze.com/httpclient-vs-restsharp/

[sebastian-sawicki]

Please provide option to configure HttpClient in merchant’s source code and inject HttpClient into CyberSource Client SDK.
The latest RestSharp.RestClient has constructor which accepts HttpClient.
https://github.com/restsharp/RestSharp/blob/dev/src/RestSharp/RestClient.cs#L99

WHY:

HttpClient has problems. Create an instance for every request and you will run into socket exhaustion. Make it a singleton and it will not respect DNS changes.
Microsoft explains it in its documentation and provides 2 solutions – either HttpClient + SocketsHttpHandler settings or HttpClientFactory with its extension methods – for connection pooling and connection lifetime management.

1. https://learn.microsoft.com/en-us/dotnet/architecture/microservices/implement-resilient-applications/use-httpclientfactory-to-implement-resilient-http-requests
2. https://learn.microsoft.com/en-us/dotnet/fundamentals/networking/http/httpclient-guidelines
3. https://learn.microsoft.com/en-us/aspnet/core/fundamentals/http-requests?view=aspnetcore-6.0
4. https://www.stevejgordon.co.uk/httpclient-connection-pooling-in-dotnet-core

Please see that RestSharp’s contributors have already noticed that RestSharp’s recommendation to always create a singleton RestClient https://restsharp.dev/v107/#restclient-lifecycle doesn’t work for all use cases. There is active issue on RestSharp GitHub restsharp/RestSharp#1791 which mentions: “The biggest problem I foresee with the way v107 is currently implemented is while it does fix the issued with connection exhaustion, it does not fix the issues with DNS resolution problems. So anyone using RestSharp v107 and singleton instances, or anyone relying on a library that does the same (like EasyPost if they accept my patches) can potentially run into DNS related problems if their application needs to respect DNS changes.” and last comment restsharp/RestSharp#1791 (comment) is also what we ask for.