Shared secret authorization with Azure SignalR Service

While testing out Azure Functions development and configuration with Azure SignalR Service, I needed a very simple key-based (shared secret) authorization mechanism so that my console-based SignalR client could connect to my Azure SignalR Service-powered hub using a very simple mechanism.

The docs and the sample showcased the negotiate endpoint returning the connection info directly:

[FunctionName("negotiate")]
public SignalRConnectionInfo Negotiate([HttpTrigger(AuthorizationLevel.Anonymous)]HttpRequest req)

But a stackoverflow answer pointed me to the solution: just the proper IActionResult using OkObjectResult with the connection info when the access key is properly validated:

[FunctionName("negotiate")]
public IActionResult Negotiate(
    [HttpTrigger(AuthorizationLevel.Anonymous, "post")] HttpRequest req,
    [SignalRConnectionInfo(HubName = "events")] SignalRConnectionInfo connectionInfo)
{
    var expectedKey = Environment.GetEnvironmentVariable("AccessKey");
    if (string.IsNullOrEmpty(expectedKey))
        return new OkObjectResult(connectionInfo);

    var accessKey = req.Query["accessKey"];
    if (StringValues.IsNullOrEmpty(accessKey) ||
        !StringValues.Equals(expectedKey, accessKey))
        return new UnauthorizedResult();

    return new OkObjectResult(connectionInfo);
}