@Value.Lazy
    public Optional<Long> serialVersion() {
      Optional<VersionMirror> version = VersionMirror.find(element());
      if (version.isPresent()) {
        return Optional.of(version.get().value());
      }

      for (MetaAnnotated metaAnnotated : metaAnnotated()) {
        Optional<Long> serialVersion = metaAnnotated.serialVersion();
        if (serialVersion.isPresent()) {
          return serialVersion;
        }
      }

      return Optional.<Long>absent();
    }
used to intern packaged created internally
value-processor/src/org/immutables/value/processor/meta/Proto.java