code: public List<String> enums() {
      return Optional.ofNullable(MoreTypes.getRawType(type))
          .map(Class::getEnumConstants)
          .filter(Objects::nonNull)
          .map(values -> Arrays.asList(values).stream()
              .map(value -> ((Enum) value).name())
              .collect(Collectors.toList())
          ).orElse(Collections.emptyList());
    }
docs: List of enum values when the {@link #type()} represents an enum.
  
  @return Enum values.