Invalid annotation tags deliver warnings that are sprinkled throughout the output listing. That's inefficient and ineffective. Warnings should be collected at the end, so they're all in one place. In addition, user should be able to determine what they want to do when an invalid annotation flag is found:
 
  a) Fatal: Immediately abort
  b) Error: Stop generating output but keep looking for new tags
     (and generate a message to that effect)
  c) Warning: List warnings at the end (the default)

I believe there is already a process for totally ignoring known annotations that aren't handled by the current doclet. The invocation of javadoc on the jdk needs to include the more common tags that are currently present. (If no such function exists, it should be created.)