Tests loading various classes (as classes and URL resources) with different
settings for contextPriorityClassLoader to make sure the restrictions on
javax.* class loading are honored.
JettyServer extends the base Jetty Server class to prevent managing any user realm information by the web.xml realm name
which is only relevant for basic and digest authentication and should not be tied to any
actual information about which security realm is in use.
This ServletHolder's sole purpose is to provide the thread's current
ServletHolder for realms that are interested in the current servlet, e.g.
current servlet name.
It is also being our servlet gbean for now.