code: private static Logger getLogger()
      {
          if(FaxClientSpiFactory.logger==null)
          {
              synchronized(FaxClientSpiFactory.class)
              {
                  if(FaxClientSpiFactory.logger==null)
                  {
                      //get logger manager
                      LoggerManager loggerManager=LoggerManager.getInstance();
  
                      //get logger
                      Logger localLogger=loggerManager.getLogger();
                      
                      //print product info
                      localLogger.logDebug(new Object[]{ProductInfo.getProductInfoPrintout()},null);
                      
                      //keep reference
                      FaxClientSpiFactory.logger=localLogger;
                  }
              }
          }
  
          return FaxClientSpiFactory.logger;
      }
docs: This function returns the internal logger for the fax4j framework.
  
  @return  The logger