code: protected function generateLegacyAutoloads()
      {
          $this->output->writeln('');
          $this->output->write('Generating legacy autoloads... ');
  
          $currentWorkingDirectory = getcwd();
  
          try {
              chdir($this->getContainer()->getParameter('ezpublish_legacy.root_dir'));
  
              $processBuilder = new ProcessBuilder(
                  array(
                      'php',
                      'bin/php/ezpgenerateautoloads.php',
                      '--quiet',
                  )
              );
  
              $process = $processBuilder->getProcess();
  
              $process->setTimeout(3600);
              $process->run(
                  function ($type, $buffer) {
                      echo $buffer;
                  }
              );
  
              chdir($currentWorkingDirectory);
  
              if (!$process->isSuccessful()) {
                  return array(
                      '- Run the following command from your ezpublish_legacy root to generate legacy autoloads:',
                      '',
                      '    <comment>php bin/php/ezpgenerateautoloads.php</comment>',
                      '',
                  );
              }
          } catch (Exception $e) {
              chdir($currentWorkingDirectory);
  
              return array(
                  'There was an error generating legacy autoloads: ' . $e->getMessage(),
                  '',
              );
          }
      }
docs: Generates legacy autoloads.
  
  @return array