allow for content-less via binary mode for CloudEventBinding

Author: erwinkramer

samples/CloudNative.CloudEvents.AspNetCoreSample/CloudEventBinding.cs

@@ -26,7 +26,7 @@ public static async ValueTask<CloudEventBinding> BindAsync(HttpContext context,
         // types such as "text/xml" could still be parsed with the current JsonEventFormatter,
         // but it's just not making it strongly typed, or anything structured (XmlNode).
         // Depending on your use-case, it may or may not be desirable to allow that.
-        if (!request.HasJsonContentType())
+        if (request.ContentLength != 0 && !request.HasJsonContentType())
         {
             return new CloudEventBinding
             {

samples/CloudNative.CloudEvents.AspNetCoreSample/CloudNative.CloudEvents.AspNetCoreSample.http

@@ -28,6 +28,14 @@ CE-Id: "{{$guid}}"
     "message": "Hello world!"
 }
 
+### Send content-less via Binary mode
+
+POST {{HostAddress}}/api/events/receive
+CE-SpecVersion: 1.0
+CE-Type: "com.example.myevent"
+CE-Source: "urn:example-com:mysource:abc"
+CE-Id: "{{$guid}}"
+
 ### Send unsupported media type (XML) via Binary mode
 
 POST {{HostAddress}}/api/events/receive