code: static Optionalish createIfOptional(TypeMirror type) {
      if (isOptional(type)) {
        return new Optionalish(MoreTypes.asDeclared(type));
      } else {
        return null;
      }
    }
docs: Returns an instance wrapping the given TypeMirror, or null if it is not any kind of Optional.
  
  @param type the TypeMirror for the original optional type, for example {@code
  Optional<String>}.