docs: public static <T> List<T> getUnique(Collection<T> collection) {
          HashSet<T> set = new HashSet<>();
          List<T> out = new ArrayList<>();
          for (T t : collection) {
              if (!set.contains(t)) {
                  out.add(t);
                  set.add(t);
              }
          }
          return out;
      }