title: How do we post messages to event grid topics?
body: <p>I have created event grid topic in azure using event schema = "Event Grid Schema".</p>
  
  <p>The next steps for me is trying to send messages to that event grid topic so the subscribers can do something when the message has been successfully received in event grid topic.</p>
  
  <p>However, I had a problem when sending the message to event grid topic. It always reject my JSON request with error "Required property 'subject' was not set. even tough, I have explicitly set the subject in my JSON post body.</p>
  
  <p>I have also add 'aeg-sas-key' value in header for authentication purposes.</p>
  
  <p>Here is an example of my JSON format:</p>
  
  <pre><code>{
      "id": "19291",
      "subject": "myapp/vehicles/motorcycles",
      "topic": "VehicleData",
      "eventType": "statusupdated",
      "eventTime": "2019-05-12T18:41:00.9584103Z",
      "data":{
           "firstName": "Jason",
           "postalAddress": "xyz"
      },
      "dataVersion": "1.0",
      "metadataVersion": "string"
    }
  </code></pre>
  
  <p>and Here is the output:</p>
  
  <pre><code>{
      "error": {
          "code": "BadRequest",
          "message": "Required property 'subject' was not set. Report '433759ee-6570-466e-ae12-a6dc5fccbfe1:5/14/2019 4:01:32 AM (UTC)' to our forums for assistance or raise a support ticket.",
          "details": [
              {
                  "code": "InputJsonInvalid",
                  "message": "Required property 'subject' was not set. Report '433759ee-6570-466e-ae12-a6dc5fccbfe1:5/14/2019 4:01:32 AM (UTC)' to our forums for assistance or raise a support ticket."
              }
          ]
      }
  }
  </code></pre>
  
  <p>Any idea why it always ask for subject even tough I have provided the subject in my JSON?</p>