code: public FileWidgetUpload getFile(final String fileId) {
  		for (FileWidgetUpload file : getFiles()) {
  			if (Util.equals(file.getFileId(), fileId)) {
  				return file;
  			}
  		}
  		return null;
  	}
docs: Retrieves the File at the given index. Will throw an {@link IndexOutOfBoundsException} if <code>index</code> is
  not in the range of the list of items.
  
  @param fileId the file id
  @return The FileWidgetUpload for the file id or null