title: How to read multiple files with MultiResourceItemReader?
body: <p>I have a <code>tar.gz</code> archive with about 1 million files. I want to use <code>MultiResourceItemReader</code> from <code>spring-batch</code> to read those files.</p>
  
  <p>Problem: the <code>MultiResourceItemReader</code> requires the <code>resources</code> set up on initialisation. But I don't want to initialize all of the 1mio files before the import starts. Instead I'd like to have the MultiResourceItemReader read the archive file by file, and pass each file through the batch import instead of allocating all files on startup.</p>
  
  <p>How could I achive this?</p>