code: public static boolean checkListsEqual(List<?> l1, List<?> l2) {
    
      // TODO (jhl388): write a test case for this method.
    
      if (null != l1 && null == l2) {
        return false;
      }
    
      if (null == l1 && null != l2) {
        return false;
      }
    
      if (null != l1) {
        for (Object e : l1) {
          if (!l2.contains(e)) {
            return false;
          }
        }
    
        for (Object e : l2) {
          if (!l1.contains(e)) {
            return false;
          }
        }
      }
      return true;
    }
docs: Checks that two lists are equal, specifically: they are both null or the both contain the same
  elements.
  
  @param l1
  The first list to check.
  @param l2
  The second list to check.
  @return True if one of the following conditions hold:
  <ol>
  <li>Both lists are null</li>
  <li>a) Neither list is null; b) for each element in list 1 an equivalent element
  exists in list 2; and c) for each element in list 2, an equivalent element exists in
  list 1</li>
  </ol>