title: Mule / AMQP / RabbitMQ: Trying to send to the default exchange
body: <p>Using Mule 3.4 with the AMQP Transport plugin and RabbitMQ, I am trying to send a message to the default AMQP exchange.  The documentation for the exchangeName attribute states "leave blank or omit for the default exchange".  However if I (a) omit it, like so:</p>
  
  <pre><code>&lt;amqp:outbound-endpoint routingKey="my.queue" connector-ref="amqpDefaultConnector" /&gt;
  </code></pre>
  
  <p>Then I get the error message: </p>
  
  <blockquote>
    <p>Element amqp:outbound-endpoint{connector-ref=amqpDefaultConnector,
    name=.test:outbound-endpoint.17, routingKey=process.task.complete}
    must have all attributes for one of the sets: [address] [ref]
    [queueName] [exchangeName] [exchangeName, queueName].</p>
  </blockquote>
  
  <p>Which seems to indicate that it is not valid to omit the attribute. However, if I (b) provide it but leave it blank, like so:</p>
  
  <pre><code>&lt;amqp:outbound-endpoint exchangeName="" routingKey="my.queue" connector-ref="amqpDefaultConnector" /&gt;
  </code></pre>
  
  <p>then I get the error message: </p>
  
  <blockquote>
    <p>java.net.URISyntaxException: Expected authority at index 7: amqp://</p>
  </blockquote>
  
  <p>I believe that the rest of my configuration and setup is correct, as using a named exchange works as expected.   Any help would be appreciated.</p>