Enable spotless for code formatting

pom.xml

@@ -76,6 +76,7 @@
   <properties>
     <mavenVersion>3.2.5</mavenVersion>
     <mojo.java.target>8</mojo.java.target>
+    <recommendedJavaBuildVersion>11</recommendedJavaBuildVersion>
     <!-- remove with parent upgrade -->
     <maven-release-plugin.version>3.0.0</maven-release-plugin.version>
     <scmpublish.content>${project.build.directory}/staging/build-helper-maven-plugin</scmpublish.content>
@@ -137,30 +138,10 @@
     </dependency>
   </dependencies>
 
-  <reporting>
-    <plugins>
-      <plugin>
-        <groupId>org.apache.maven.plugins</groupId>
-        <artifactId>maven-checkstyle-plugin</artifactId>
-        <!-- version inherited -->
-        <configuration>
-          <configLocation>config/maven_checks.xml</configLocation>
-          <headerLocation>header.txt</headerLocation>
-        </configuration>
-      </plugin>
-    </plugins>
-  </reporting>
-
   <profiles>
 
     <profile>
       <id>run-its</id>
-      <activation>
-        <property>
-          <name>skipTests</name>
-          <value>!true</value>
-        </property>
-      </activation>
       <build>
         <plugins>
           <plugin>
@@ -188,6 +169,28 @@
       </build>
     </profile>
 
+    <profile>
+      <id>java11+</id>
+      <activation>
+        <jdk>[11,)</jdk>
+      </activation>
+      <build>
+        <plugins>
+          <plugin>
+            <groupId>com.diffplug.spotless</groupId>
+            <artifactId>spotless-maven-plugin</artifactId>
+          </plugin>
+          <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-checkstyle-plugin</artifactId>
+            <configuration>
+              <configLocation>${checkstyle.spotless.config}</configLocation>
+            </configuration>
+          </plugin>
+        </plugins>
+      </build>
+    </profile>
+
     <!-- This plugin's configuration is used to store Eclipse m2e settings only. It has no influence on the Maven build itself. -->
     <profile>
       <id>only-eclipse</id>