Issue #511: update checkstyle to 10.15.0

Author: muhlba91

README.md

@@ -17,6 +17,7 @@ Compatibility matrix from Checkstyle:
 
 | Checkstyle Plugin | Sonar min | Sonar max | Checkstyle | Jdk |
 |-------------------|-----------|-----------|------------|-----|
+| 10.15.0           | 9.9       | 10.0+     | 10.15.0    | 11  |
 | 10.14.2           | 9.9       | 10.0+     | 10.14.2    | 11  |
 | 10.14.1           | 9.9       | 10.0+     | 10.14.1    | 11  |
 | 10.12.5           | 9.0       | 10.0+     | 10.12.5    | 11  |

pom.xml

@@ -93,7 +93,7 @@
   </ciManagement>
 
   <properties>
-    <checkstyle.version>10.14.2</checkstyle.version>
+    <checkstyle.version>10.15.0</checkstyle.version>
     <sonar.version>9.9.4.87374</sonar.version>
     <sonar.api-version>9.9.0.229</sonar.api-version>
     <maven.sevntu.checkstyle.plugin.version>1.44.1</maven.sevntu.checkstyle.plugin.version>