buildbot failure in on wicket-master

[buildbot]

The Buildbot has detected a new failure on builder wicket-master while building 
wicket. Full details are available at:
    https://ci.apache.org/builders/wicket-master/builds/245

Buildbot URL: https://ci.apache.org/

Buildslave for this Build: hemera_ubuntu

Build Reason: The SingleBranchScheduler scheduler named 
'on-wicket-master-commit' triggered this build
Build Source Stamp: [branch master] b7bbb8d17232373120bc26b3b9247046399e9840
Blamelist: 

BUILD FAILED: failed compile

Sincerely,
 -The Buildbot