code: public static boolean isValid(final String value) {
          if (value == null) {
              return true;
          }
          final String uuidPattern = "^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-" + "[0-9a-f]{4}-[0-9a-f]{12}$";
          return Pattern.matches(uuidPattern, value);
      }
docs: Verifies that a given string is a valid UUID.
  
  @param value
  Value to check. A <code>null</code> value returns <code>true</code>.
  
  @return TRUE if it's a valid key, else FALSE.