code: public static StringBuilder toStringBuilder(Collection<? extends Object> collection, String delimiter) {
          StringBuilder sb = new StringBuilder(collection.size() * 20);
          for (Iterator<? extends Object> it = collection.iterator(); it.hasNext();) {
              Object cs = it.next();
              sb.append(cs);
              if (it.hasNext()) {
                  sb.append(delimiter);
              }
          }
          return sb;
      }
docs: Transform a collection of objects to a delimited String.
  
  @param collection the collection to transform.
  @param delimiter the delimiter used to delimit the Strings.
  @return a StringBuilder with all the elements of the collection.