question: private void retryFailedInterfaces ( ) { final Level level = multicastInterfacesSpecified ? Level . INFO : Level . FINE ; if ( logger . isLoggable ( level ) ) logger . log ( level , "retryFailedInterfaces() will attempt to enable " + failedInterfaces . size ( ) + " interfaces..." ) ; for ( Iterator < NetworkInterface > i = failedInterfaces . iterator ( ) ; i . hasNext ( ) ; ) { NetworkInterface nic = i . next ( ) ; long startTime = LogHelper . getCurrTimeIfNeeded ( logger , level ) ; try { if ( nic != null ) socket . setNetworkInterface ( nic ) ; socket . joinGroup ( requestAddr ) ; i . remove ( ) ; if ( logger . isLoggable ( level ) ) { String message = nic == null ? "Enabled default interface" : "Enabled " + nic ; LogHelper . logDuration ( logger , level , startTime , message ) ; } } catch ( IOException e ) { if ( logger . isLoggable ( level ) ) { String message = nic == null ? "Failed to enabled default interface" : "Failed to enabled " + nic ; LogHelper . logDuration ( logger , level , startTime , message ) ; } } } }
target:  Attempts to configure each interface contained in the failedInterfaces list, removing it from the list if configuration succeeds.  The null value is used to indicate the default network interface.