buildbot failure in on wicket-branch-1.4.x

[buildbot]

The Buildbot has detected a new failure on builder wicket-branch-1.4.x while 
building . Full details are available at:
    https://ci.apache.org/builders/wicket-branch-1.4.x/builds/1

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

Buildslave for this Build: bb_slave1_ubuntu

Build Reason: forced: by IRC user <dashorst> on channel ##wicket: None
Build Source Stamp: [branch wicket-1.4.x] HEAD
Blamelist: 

BUILD FAILED: failed compile

Sincerely,
 -The Buildbot