docs: public static String collectionAsString(Collection<?> collection, String separator) {
  
          StringBuffer string = new StringBuffer(128);
          Iterator<?> it = collection.iterator();
          while (it.hasNext()) {
              string.append(it.next());
              if (it.hasNext()) {
                  string.append(separator);
              }
          }
          return string.toString();
      }