docs: protected void onBackupWithoutLoadedSession( @Nonnull final String sessionId, @Nonnull final String requestId,
              @Nonnull final BackupSessionService backupSessionService ) {
  
          if ( !_sessionIdFormat.isValid( sessionId ) ) {
              return;
          }
  
          try {
  
              final long start = System.currentTimeMillis();
  
              final String validityKey = _sessionIdFormat.createValidityInfoKeyName( sessionId );
              final SessionValidityInfo validityInfo = loadSessionValidityInfoForValidityKey( validityKey );
              if ( validityInfo == null ) {
                  _log.warn( "Found no validity info for session id " + sessionId );
                  return;
              }
  
              final int maxInactiveInterval = validityInfo.getMaxInactiveInterval();
              final byte[] validityData = encode( maxInactiveInterval, System.currentTimeMillis(),
                      System.currentTimeMillis() );
              // fix for #88, along with the change in session.getMemcachedExpirationTimeToSet
              final int expiration = maxInactiveInterval <= 0 ? 0 : maxInactiveInterval;
              final Future<Boolean> validityResult = _storage.set( validityKey, toMemcachedExpiration(expiration), validityData );
              if ( !_manager.isSessionBackupAsync() ) {
                  validityResult.get( _manager.getSessionBackupTimeout(), TimeUnit.MILLISECONDS );
              }
  
              /*
               * - ping session
               * - ping session backup
               * - save validity backup
               */
              final Callable<?> backupSessionTask = new OnBackupWithoutLoadedSessionTask( sessionId,
                      _storeSecondaryBackup, validityKey, validityData, maxInactiveInterval );
              _executor.submit( backupSessionTask );
  
              if ( _log.isDebugEnabled() ) {
                  _log.debug( "Stored session validity info for session " + sessionId );
              }
  
              _stats.registerSince( NON_STICKY_ON_BACKUP_WITHOUT_LOADED_SESSION, start );
  
          } catch( final Throwable e ) {
              _log.warn( "An error when trying to load/update validity info.", e );
          }
  
      }