Merge branch 'maven-warning-fixes' into 'master'

Fix maven warnings while building the product

See merge request entgra/carbon-device-mgt!463

components/application-mgt/pom.xml

@@ -50,6 +50,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-checkstyle-plugin</artifactId>
+                <version>${maven.checkstyle.vesion}</version>
             </plugin>
         </plugins>
         <pluginManagement>