Cleanup file streaming utilities (#559)

* Cleanup file streaming.

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

* Added missing comments.

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

* Fix typo.

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

* Split utility class.

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

* Dependency cleanup.

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

* Add missing dependency,

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

* Remove repository api dependency from rest core.

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

* Fix build and sonar issues.

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

* Remove custom ConstraintViolationException

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

* RequestMapping should be public.

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

* Fix errors.

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

* Removed dead code.

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

* Not null

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

* Fix nullpointer.

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

* Code cleanup.

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

hawkbit-runtime/hawkbit-update-server/src/main/java/org/eclipse/hawkbit/app/StreamAwareErrorController.java

@@ -41,7 +41,7 @@ public class StreamAwareErrorController extends BasicErrorController {
     }
 
     @RequestMapping(produces = MediaType.APPLICATION_OCTET_STREAM_VALUE)
-    ResponseEntity<Void> errorStream(final HttpServletRequest request, final HttpServletResponse response) {
+    public ResponseEntity<Void> errorStream(final HttpServletRequest request, final HttpServletResponse response) {
         final HttpStatus status = getStatus(request);
         return new ResponseEntity<>(status);
     }