code: public static <E> List<E> compact(final List<E> list) {
          return filter(list, new Predicate<E>() {
              @Override
              public boolean test(E arg) {
                  return !String.valueOf(arg).equals("null") && !String.valueOf(arg).equals("0")
                      && !String.valueOf(arg).equals("false") && !String.valueOf(arg).equals("");
              }
          });
      }
docs: /*
  Documented, #compact