Fix sonar issues and add DMF tests for maintenance window feature (#655)

* Fix sonar issues.

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

* POM cleanup and more sonar issues fixed.

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

* Remove unneeded JavaDocs.

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

* More sonar issues.

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

* More issues.

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

* Adapt maintenance window to naming.

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

* Add DMF tests.

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

* Readibility.

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

* Typos fixed.

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

hawkbit-dmf/hawkbit-dmf-api/src/main/java/org/eclipse/hawkbit/dmf/amqp/api/EventTopic.java

@@ -32,6 +32,6 @@ public enum EventTopic {
     /**
      * Topic when sending a download only task, skipping the install.
      */
-    DOWNLOAD_AND_SKIP;
+    DOWNLOAD;
 
 }