code: public static String[] getRDNs(String rdnStr) {
          StringTokenizer st = new StringTokenizer(rdnStr.toLowerCase(), "+");
          ArrayList<String> list = new ArrayList<String>();
          while (st.hasMoreTokens()) {
              String rdn = st.nextToken();
              list.add(rdn);
          }
          return list.toArray(new String[0]);
      }
docs: Returns array of RDN attribute types from the given RDN string.
  RDN string may contain multiple RDNs separated by "+".
  For example, "uid+mail" string will return [uid, mail].
  
  @param rdnStr the RDN string
  @return the array of separated RDNs.