private static int getVersion() {
    if (ourVersion == -1) {
      int version = BASE_VERSION;
      for (FileBasedIndexInfrastructureExtension ex : FileBasedIndexInfrastructureExtension.EP_NAME.getExtensionList()) {
        int extensionVersion = ex.getVersion();
        // move rocksdb versioning outside
        if (extensionVersion != -1) {
          version = 31 * version + extensionVersion;
        }
      }
      ourVersion = version;
    }
    return ourVersion;
  }
private static int getVersion()