title: collectd, java plugin: Cannot find the API class org.collectd.api.Collectd
body: <p>I'm trying to run java plugin GenericJMX on collectd but I'm stuck on collectd API. </p>
  
  <p>I got this message: java.lang.UnsupportedClassVersionError: org/collectd/api/Collectd has been compiled by a more recent version of the Java Runtime (class file version 54.0), this version of the Java Runtime only recognizes class file versions up to 52.0</p>
  
  <p>On my system there is installed java version "11.0.1" 2018-10-16 LTS, but this log is telling me that I only recognize versions up to 52.0, which should be version 8. </p>
  
  <p>This is some internal JRE of collectd? </p>