Fix DMF update cancel message (#397)

* Fix bug where DMF sends cancel for DDI targets.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

* Fix nullpointer when event consumer access target info.

Signed-off-by: kaizimmerm <kai.zimmermann@bosch-si.com>

hawkbit-dmf-amqp/src/main/java/org/eclipse/hawkbit/amqp/AmqpMessageDispatcherService.java

@@ -156,6 +156,10 @@ public class AmqpMessageDispatcherService extends BaseAmqpService {
 
     void sendCancelMessageToTarget(final String tenant, final String controllerId, final Long actionId,
             final URI address) {
+        if (!IpUtil.isAmqpUri(address)) {
+            return;
+        }
+
         final Message message = getMessageConverter().toMessage(actionId,
                 createConnectorMessageProperties(tenant, controllerId, EventTopic.CANCEL_DOWNLOAD));