code: public FileRepositoryCollection createFileRepositoryCollection(File file) {
      Class<? extends FileRepositoryCollection> clazz;
  
      String extension =
          FileExtensionUtils.findExtensionFromPossibilities(
              file.getName(), fileRepositoryCollections.keySet());
  
      clazz = fileRepositoryCollections.get(extension);
  
      if (clazz == null) {
        throw new MolgenisDataException("Unknown extension for file '" + file.getName() + "'");
      }
  
      Constructor<? extends FileRepositoryCollection> ctor;
      try {
        ctor = clazz.getConstructor(File.class);
      } catch (Exception e) {
        throw new MolgenisDataException(
            "Exception creating ["
                + clazz
                + "]  missing constructor FileRepositorySource(File file)");
      }
  
      FileRepositoryCollection fileRepositoryCollection = BeanUtils.instantiateClass(ctor, file);
      autowireCapableBeanFactory.autowireBeanProperties(
          fileRepositoryCollection, AutowireCapableBeanFactory.AUTOWIRE_BY_TYPE, false);
      try {
        fileRepositoryCollection.init();
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
      return fileRepositoryCollection;
    }
docs: Factory method for creating a new FileRepositorySource
  
  <p>For example an excel file