Allow invalid CosmosDB Emulator certificate with DocumentClient

We have a project which is using the older DocumentClient based CosmosDB SDK. Getting this project to communicate with a Docker hosted CosmosDB emulator turned out to be a hassle.

The new SDK contains the following functionality for ignoring certificate issues:

CosmosClientOptions cosmosClientOptions = new CosmosClientOptions()
{
    HttpClientFactory = () =>
    {
        HttpMessageHandler httpMessageHandler = new HttpClientHandler()
        {
            ServerCertificateCustomValidationCallback = HttpClientHandler.DangerousAcceptAnyServerCertificateValidator
        };

        return new HttpClient(httpMessageHandler);
    },
    ConnectionMode = ConnectionMode.Gateway
};

CosmosClient client = new CosmosClient(endpoint, authKey, cosmosClientOptions);

But the DocumentClient works little differently. But the good thing is that we can pass in a HttpClientHandler when creating the DocumentClient. So to ignore the cert issues when developing locally, one can use:

                    var handler = new HttpClientHandler();
                    handler.ClientCertificateOptions = ClientCertificateOption.Manual;
                    handler.ServerCertificateCustomValidationCallback = 
                        (httpRequestMessage, cert, cetChain, policyErrors) =>
                        {
                            return true;
                        };

                    client = new DocumentClient(
                        new Uri(endPointUrl),
                        primaryKey,
                        handler, connectionPolicy
                    );

If you need to configure serializer settings and the http client handler, things are a bit harder as there is not suitable public constructor in DocumentClient for configuring both. Reflection to rescue:

                    var handler = new HttpClientHandler();
                    handler.ClientCertificateOptions = ClientCertificateOption.Manual;
                    handler.ServerCertificateCustomValidationCallback = 
                        (httpRequestMessage, cert, cetChain, policyErrors) =>
                        {
                            return true;
                        };

                    client = new DocumentClient(
                        new Uri(endPointUrl),
                        primaryKey,
                        handler, connectionPolicy
                    );
                    
                    var prop = client.GetType().GetField("serializerSettings", System.Reflection.BindingFlags.NonPublic
                                                               | System.Reflection.BindingFlags.Instance);
                    prop.SetValue(client, serializerSettings);