Set to Java8, bc even 'mvn -f pom-java8.xml' picks it up from pom.xml (Maven bug?)

Author: egonw

pom.xml

@@ -202,7 +202,7 @@
                                     <version>3.6.3</version>
                                 </requireMavenVersion>
                                 <requireJavaVersion>
-                                    <version>11</version>
+                                    <version>8</version>
                                 </requireJavaVersion>
                             </rules>
                         </configuration>