code: public String getEmpty() {
      String empty = className.startsWith("java.util.") ? ".empty()" : ".absent()";
      return TypeEncoder.encodeRaw(optionalType) + empty;
    }
docs: Returns a string representing the method call to obtain the empty version of this Optional.
  This will be something like {@code "Optional.empty()"} or possibly {@code
  "java.util.Optional.empty()"}. It does not have a final semicolon.
  
  <p>This method is public so that it can be referenced as {@code p.optional.empty} from
  templates.