code: private String getPart(int pos) {
      String value = this.getValue();
      if (value == null) {
        return null;
      }
      String[] parts = value.split("/");
      return parts.length >= pos + 1 ? parts[pos] : null;
    }
docs: Extracts the given part from the unique identifier.
  
  @param pos
  position
  @return the part or {@code null}