presto-hive/src/main/java/io/prestosql/plugin/hive/authentication/CachingKerberosHadoopAuthentication.java/CachingKerberosHadoopAuthentication/getUserGroupInformation
class CachingKerberosHadoopAuthentication:    @Override
    public synchronized UserGroupInformation getUserGroupInformation()
    {
        if (nextRefreshTime < System.currentTimeMillis() || userGroupInformation == null) {
            userGroupInformation = requireNonNull(delegate.getUserGroupInformation(), "delegate.getUserGroupInformation() is null");
            nextRefreshTime = calculateNextRefreshTime(userGroupInformation);
        }
        return userGroupInformation;
    }