docs: public static Predicate<Object> byFixedGeneration(final long generation) {
  		if (generation < 0) {
  			throw new IllegalArgumentException(format(
  				"The number of generations must greater than one, but was %d",
  				generation
  			));
  		}
  
  		return new Predicate<Object>() {
  			private final AtomicLong _current = new AtomicLong();
  			@Override
  			public boolean test(final Object o) {
  				return _current.incrementAndGet() <= generation;
  			}
  		};
  	}