Feature/fix sonar warnings (#1226)

* Fixed sonar warnings

- "Cognitive Complexity"
- "Do not use replaceAll when not using a regex"
- java:S5869 - Character classes in regular expressions should not contain the same character twice
- Improved bad name
- Typos
- reduced code duplications
- Replaced hand-made wait-utility with Awaitility
- Log messages
- Duplicate code
- Typos
- Removed Thread.sleep, instead relaxed check condition
- Removed use of deprecated API
- Removed use of deprecated API
- Added supress-warnings as I do not see a better way to write the tests
- Removed Thread.sleep / redundant functionality to Awaitility
- Fixed other warnings (use isZero, isEmpty, hasToString)
- Removed/Reduced duplicate code
- Added generics
- Fixed asserts
- removed: field.setAccessible(true) actually should not be needed for public static fields!
- Too long constructor passes arguments in wrong order - how surprisingly...
- Clean-up use of varargs arguments
- Fixed regex
- Fixed typos and other minor stuff
- Making public constructors protected in abstract classes
- Swapped expected and asserted argument
- volatile not enough for syncing threads
- volatile not enough for syncing threads
- out-commented code
- Made regex not-greedy, added tests for verification
- Avoid exposure of thread-local member var

Signed-off-by: Peter Vigier <Peter.Vigier@bosch.io>

* Fixed Sonar warnings

* License header fix

Signed-off-by: Peter Vigier <Peter.Vigier@bosch.io>

* License header fix #2

Signed-off-by: Peter Vigier <Peter.Vigier@bosch.io>

* Fixing review findings

Signed-off-by: Peter Vigier <Peter.Vigier@bosch.io>

* Fixing tests

- Fixed '&' usage in javadoc and typos
- Fixing some warnings

Signed-off-by: Peter Vigier <Peter.Vigier@bosch.io>

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

@@ -56,7 +56,7 @@ public class DefaultAmqpMessageSenderService extends BaseAmqpService implements
             LOGGER.debug("Sending message to exchange {} with correlationId {}", exchange, correlationId);
         }
 
-        getRabbitTemplate().send(exchange, null, message, new CorrelationData(correlationId));
+        getRabbitTemplate().send(exchange, "", message, new CorrelationData(correlationId));
     }
 
     protected static boolean isCorrelationIdEmpty(final Message message) {