code: public <E extends Comparable<E>> boolean sort(List<E> input)
      {
          if (input == null) {
              return false;
          }
          try {
              Collections.sort(input);
              return true;
          } catch (UnsupportedOperationException ex) {
              return false;
          }
      }
docs: Sort the elements within a list according to their natural order. The input list is modified in place, so this
  operation will succeed only if the list is modifiable.
  
  @param <E> the type of the elements in the list
  @param input the list to sort
  @return {@code true} if the list was successfully sorted, {@code false} otherwise