Complete API for action cancelation. (#643)

* Complete API for action cancelation.

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

* Fix content bug

docs/src/main/resources/documentation/interfaces/dmf-api.md

@@ -113,6 +113,7 @@ Payload Template
 "message":["String"]
 }
 ```
+
 Possible actionStatus
 
 | Header          | Description                        |                                                
@@ -155,12 +156,25 @@ Possible actionStatus
 |-----------------------------|----------------------------------|-------------------------------------|----------------
 | content_type                 | The content type of the payload  | String                              | true
 
-**Example Header**
+Payload Template
+
+```json
+{
+"actionId": long
+}
+```
+
+**Example Header and payload**
 
 | Headers                               | MessageProperties               |                                                              
 |---------------------------------------|---------------------------------|
 | type=EVENT <br /> tenant=tenant123 <br /> thingId=abc  <br /> topic=CANCEL\_DOWNLOAD   | content_type=application/json  
 
+```json
+{
+"actionId":137
+}
+```
 
 After this message has been sent, an action status event with either actionStatus=CANCELED or actionStatus=CANCEL_REJECTED has to be returned.