The use of libraries using awt components creates ClassLoader Memory Leaks. This is because the first call to the sun AppContext class makes a static reference to the current class loader.
Same thing goes with the creation of the AWT Event Queue, as an example the use of the class java.awt.Color makes a static init call to java.awt.Toolkit which creates an AWT EventQueue despite the headless mode. The EventQueue also keep a reference to the current context with the class loader.

The current work around I've found is to add a call to:

java.awt.Toolkit.getDefaultToolkit();

before the application gets loaded.
This causes the EventQueue to be created and the AppContext to be initialized.
Then, as the AWT static references are final, I get rid of this issue for the rest of the server lifecycle.
I put this code in org.jboss.as.server.Main, just after line 91. However a proper solution would be to use org.apache.catalina.core.JreMemoryLeakPreventionListener which is present in the JBoss Web jar but not used... (cf. https://community.jboss.org/thread/164760 ) However the Tomcat code deals only with the AppContext, not the EventQueue!