Remove accessibility modification
The z2 worker thread is forcibly clearing thread locals upon return of threads to the thread pool.
This was done as Tomcat Jasper uses a thread local page context pool that was - previously at least - not released automatically.
This should be removed for cleanliness now as the problem does not seem to exist anymore.
Otherwise the system property
org.apache.jasper.runtime.JspFactoryImpl.USE_POOL="false" should fix the problem as well.