Java 7 diamonds
WICKET-5315 PriorityHeaderItem+OnDomReadyHeaderItem has no priority in Ajax response
WICKET-5316: fixed synchronization problem in page access
WICKET-5316: boolean flag should be volatile
WICKET-5316: testcase showing the problem with lock releases
Write character instead of String where possible
WICKET-5322 "Source code" link doesn't work at wicket-library.com

Simplify SourcesPage.
Add log4j as compile dependency because the examples failed at start with ClassNotFoundException org/apache/log4j/Level
WICKET-5319 do not encrypt full urls