code: public Identifier extractPartAfterLastDot() {
      String part = BaseUtils.extractPartAfterLastDot(identifier());
      return Identifier.create(
          part, location().offsetStartCol(identifier().length() - part.length()));
    }
docs: Gets the part after the last dot in a dotted identifier. If there are no dots, returns the
  whole identifier.
  
  <p><b>Important:</b> The input must be a dotted identifier. This is not checked.