Major Description
From this review: http://review.couchbase.org/#/c/72835/ Matt Ingenthron asks: "... is this normal on .NET Core? It seems odd to me that something like HttpClient can have a different approach even down to a per-Linux distro basis."
This ticket is to spend some time looking into this and come up with a generally acceptable approach.
The underlying HttpClient implementation uses a wrapper around libcurl called CurlHandler. Within this implementation, there are various settings which if not supported by a particular version of Curl, will throw a (PlatformNotSupportedException) https://docs.microsoft.com/en-us/dotnet/core/api/system.platformnotsupportedexception. MaxConnectionsPerServer is can example of a setting which may or may not be supported by a particular version of libcurl installed on the host machine: https://github.com/dotnet/corefx/blob/master/src/System.Net.Http/src/System/Net/Http/Unix/CurlHandler.cs#L351-L373
For this particular setting (MaxConnectionsPerServer), the following settings options are used: https://curl.haxx.se/libcurl/c/CURLMOPT_MAX_HOST_CONNECTIONS.html
This was added in Curl 7.30.0.