Contrib: remove superflous sling.java.version=6 as it's the default now

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1687508 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index 1d270fb..accf815 100644
--- a/pom.xml
+++ b/pom.xml
@@ -38,7 +38,6 @@
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-    <sling.java.version>6</sling.java.version>
   </properties>
 
   <scm>