With a few lines of code you can expose a custom principal and fetch entitlements from whatever store you like.
External libraries become obsolete and your WAR stays leaner:
[See also an in-depth discussion in the "Real World Java EE Patterns--Rethinking Best Practices" book (Second Iteration, "Green Book"), page 161 (Sample "Principal Enricher") in, chapter "Re-Injector"]
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See you at Java EE Workshops at MUC Airport, particularly at the Effective JavaEE workshop!