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-rest/hawkbit-mgmt-resource/src/main/java/org/eclipse/hawkbit/mgmt/rest/resource/MgmtRolloutResource.java

@@ -10,7 +10,6 @@ package org.eclipse.hawkbit.mgmt.rest.resource;
 
 import java.util.List;
 import java.util.stream.Collectors;
-
 import javax.validation.ValidationException;
 
 import org.eclipse.hawkbit.mgmt.json.model.PagedList;
@@ -29,6 +28,7 @@ import org.eclipse.hawkbit.repository.TargetFilterQueryManagement;
 import org.eclipse.hawkbit.repository.builder.RolloutCreate;
 import org.eclipse.hawkbit.repository.builder.RolloutGroupCreate;
 import org.eclipse.hawkbit.repository.exception.EntityNotFoundException;
+import org.eclipse.hawkbit.repository.exception.RSQLParameterSyntaxException;
 import org.eclipse.hawkbit.repository.model.DistributionSet;
 import org.eclipse.hawkbit.repository.model.Rollout;
 import org.eclipse.hawkbit.repository.model.RolloutGroup;
@@ -108,17 +108,22 @@ public class MgmtRolloutResource implements MgmtRolloutRestApi {
 
         // first check the given RSQL query if it's well formed, otherwise and
         // exception is thrown
-        targetFilterQueryManagement.verifyTargetFilterQuerySyntax(rolloutRequestBody.getTargetFilterQuery());
-
-        final DistributionSet distributionSet = distributionSetManagement
-                .getValidAndComplete(rolloutRequestBody.getDistributionSetId());
+        final String targetFilterQuery = rolloutRequestBody.getTargetFilterQuery();
+        if (targetFilterQuery == null) {
+            // Use RSQLParameterSyntaxException due to backwards compatibility
+            throw new RSQLParameterSyntaxException("Cannot create a Rollout with an empty target query filter!");
+        }
+        targetFilterQueryManagement.verifyTargetFilterQuerySyntax(targetFilterQuery);
+        final DistributionSet distributionSet = distributionSetManagement.getValidAndComplete(
+                rolloutRequestBody.getDistributionSetId());
         final RolloutGroupConditions rolloutGroupConditions = MgmtRolloutMapper.fromRequest(rolloutRequestBody, true);
 
         final RolloutCreate create = MgmtRolloutMapper.fromRequest(entityFactory, rolloutRequestBody, distributionSet);
 
         Rollout rollout;
         if (rolloutRequestBody.getGroups() != null) {
-            final List<RolloutGroupCreate> rolloutGroups = rolloutRequestBody.getGroups().stream()
+            final List<RolloutGroupCreate> rolloutGroups = rolloutRequestBody.getGroups()
+                    .stream()
                     .map(mgmtRolloutGroup -> MgmtRolloutMapper.fromRequest(entityFactory, mgmtRolloutGroup))
                     .collect(Collectors.toList());
             rollout = rolloutManagement.create(create, rolloutGroups, rolloutGroupConditions);