Resolve "CheckStyle Konfiguration"

feature: add checkstyle config

client/pom.xml

@@ -65,17 +65,11 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
-                <version>${maven-compiler-plugin.version}</version>
-                <configuration>
-                    <source>11</source>
-                    <target>11</target>
-                </configuration>
             </plugin>
             <plugin>
                 <!-- Build an executable JAR -->
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-jar-plugin</artifactId>
-                <version>3.2.2</version>
                 <configuration>
                     <archive>
                         <manifest>
@@ -89,7 +83,6 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-shade-plugin</artifactId>
-                <version>3.3.0</version>
                 <executions>
                     <execution>
                         <phase>package</phase>