wicket facebook,6.15 Circular dependency detected

Hi,

I was attempting to upgrade to Wicket 6.15.0 from 6.5.0 in order to use

<wicket:header-items/>

As described in
http://wicketinaction.com/2014/03/header-contributions-positioning/

This should nicely solve an issue I'm currently having in the HTML rather
than the Java where i am using WRO4J to minimise and join javascript and
CSS . I am also using wicket-facebook 6.15.0.

I have run into a problem when i run my application. I get an error after
facebooksdk.java line 99 The following error is thrown.

org.apache.wicket.resource.CircularDependencyException: Circular
dependency detected in the dependency chain
[JavaScriptReferenceHeaderItem(scope: org.apache.wicket.Application;
name: ; locale: null; style: null; variation: null, null)].
JavaScriptReferenceHeaderItem(scope: org.apache.wicket.Application;
name: ; locale: null; style: null; variation: null, null) is already
in the chain.

It seems that for some reason a null reference is being added to the
header.

I do not get this error in 6.5.0.

Is there some obvious change i am missing between the versions that can
point me in the right direction?