code: public Set<Element> filter(RoundEnvironment roundEnv) {
  		Set<Element> result=new HashSet<Element>();		
  		for (Class<? extends Annotation> annotation: getSupportedAnnotationClasses()) {
  			result.addAll(roundEnv.getElementsAnnotatedWith(annotation));	
  		}
  		
  		return result;
  		
  	}
docs: Filter.
  
  @param roundEnv the round env
  @return the sets the