private static IServiceCollection AddSignalRServiceCore()

in src/Microsoft.Azure.SignalR.Management/DependencyInjectionExtensions.cs [83:133]
43 lines of code
3 McCabe index (conditional complexity)

    private static IServiceCollection AddSignalRServiceCore(this IServiceCollection services)
    {
        services.AddSingleton<IServiceManager, ServiceManagerImpl>();
        services.PostConfigure<ServiceManagerOptions>(o => o.ValidateOptions());
        var tempServices = new ServiceCollection()
            .AddSingleton<IEndpointRouter, AutoHealthCheckRouter>()
            .AddSignalR()
            .AddAzureSignalR<CascadeServiceOptionsSetup>().Services
            .Where(service => service.ServiceType != typeof(IServiceConnectionContainer))
            .Where(service => service.ServiceType != typeof(IHostedService));
        services.Add(tempServices);
        // Remove the JsonHubProtocol and add new one.
        // On .NET Standard 2.0, registering multiple hub protocols with the same name is forbidden.
        services.Replace(ServiceDescriptor.Singleton<IHubProtocol>(sp =>
        {
            var serviceManagerOptions = sp.GetRequiredService<IOptions<ServiceManagerOptions>>().Value;
            var objectSerializer = serviceManagerOptions.ObjectSerializer;
            if (objectSerializer != null)
            {
                return new JsonObjectSerializerHubProtocol(objectSerializer);
            }
#pragma warning disable CS0618 // Type or member is obsolete
            // The default protocol is different for historical reason.
            return serviceManagerOptions.ServiceTransportType == ServiceTransportType.Transient ?
                new JsonObjectSerializerHubProtocol(new NewtonsoftJsonObjectSerializer(serviceManagerOptions.JsonSerializerSettings))
                :
                new JsonHubProtocol();
#pragma warning restore CS0618 // Type or member is obsolete
            }));
            //add dependencies for persistent mode only
            services
                .AddSingleton<ConnectionFactory>()
                .AddSingleton<IConnectionFactory, ManagementConnectionFactory>()
                .AddSingleton<ConnectionDelegate>((connectionContext) => Task.CompletedTask)
                .AddSingleton<IServiceConnectionFactory, ServiceConnectionFactory>()
                .AddSingleton<MultiEndpointConnectionContainerFactory>()
                .AddSingleton<IConfigureOptions<HubOptions>, ManagementHubOptionsSetup>();

            //add dependencies for transient mode only
            services.AddSingleton<PayloadBuilderResolver>();

            services.AddRestClient();
            services.AddSingleton<NegotiateProcessor>();
#if NET7_0_OR_GREATER
            services.AddSingleton<IClientInvocationManager, WeakClientInvocationManager>();
#else
            services.AddSingleton<IClientInvocationManager, DummyClientInvocationManager>();
#endif

            return services.TrySetProductInfo();
        }