i think i'd prefer to have an isEnabled() in base annotation handler that by default returns true and can be overridden by each handler to return what ever it needs to return. also I'd say to have the option check in the isEnabled() and not passing a boolean in the constructor.

@Override
public boolean isEnabled() {
    return environment.getOptionBooleanValue(OPTION_TRACE);
}

also the check if a processor should run (if(isEnabled())) should be at the place where the methods are called.

if(processor.isEnabled()) {
  processor.validate(...);
  processor.process(...);
}

or if you do not want to have the check wherever validate and/or process are called add a new method that is called and that one does the enabled check and call the concrete validation/processing. (but i think that is a bit to much)

if you want to keep the current implementation just remove one of the two empty lines in TraceHandler :P

Thanks @dodgex! I will refactor it for the isEnabled() method. I think it is not a breaking change because the default implementation will retain the old behaviour.

Superseded by #1782 .