use sling.java.version and set encoding
diff --git a/pom.xml b/pom.xml
index e35e465..924f774 100644
--- a/pom.xml
+++ b/pom.xml
@@ -36,6 +36,9 @@
 
   <properties>
     <groovy.version>2.4.9</groovy.version>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+    <sling.java.version>8</sling.java.version>
   </properties>
 
   <scm>