@Transactional
  public ExtensionEntity merge(ExtensionEntity extension) {
    return entityManagerProvider.get().merge(extension);
  }
Merge the specified extension with the existing extension in the database.

@param extension
         the extension to merge (not {@code null}).
@return the updated extension with merged content (never {@code null}).
ambari-server/src/main/java/org/apache/ambari/server/orm/dao/ExtensionDAO.java