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-repository/hawkbit-repository-core/pom.xml

@@ -35,7 +35,7 @@
       <dependency>
          <groupId>com.github.ben-manes.caffeine</groupId>
          <artifactId>caffeine</artifactId>
-      </dependency>   
+      </dependency>
       <dependency>
          <groupId>org.springframework</groupId>
          <artifactId>spring-context-support</artifactId>