Azure Stream Analytics and user properties on Azure ServiceBus Queues

When you connect Azure Stream Analytics to a Azure ServiceBus queue or topic, you are able to set User Properties and System Properties. For the user properties this works quite straight forward. Each column out of your query that is listed in the output definition as Property Column will be added as a User Property on the outgoing message. Only caveat is that the column will not be part of the body of the outgoing message. 

How to use the System Properties seems a bit strange. The information on the tooltip as the definition part is as follow:

A JSON-formatted collection of name/value pairs of System Property names and output columns to be populated on Service Bus messages. e.g. { "MessageId": "column1", "PartitionKey": "column2"}

So, in my first attempt I created this definition:

{"CorrelationId": "myCorrelationId" }

I defined the field myCorrelationId in the query and expected it all to work. But no output was generated. How come? Propably because the definition caused an error.

The solution was to not name the field myCorrelationId, but column1. Go figure. So my value for the System Property columns now is:

{"CorrelationId": "column1"}