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Auto components caused some problems due to their special lifecycle - they appear only during the rendering process. This will simplify component queueing, resolvers+auto components, problems with enclosures, ...
Java 7 as a minimum
Java 7 has nice support for generics, better annotations, and Java 6 is reaching its end of life pretty soon.
Servlet 3 as a minimum
While we opted to not require servlet 3 for wicket 6, it has bitten us a couple of times solving issues in wicket 6. Servlet 3 has been out for ages, so we should move with the times.