code: public static Properties processUserData( Properties properties, File outputDirectory ) throws IOException {
  
  		interceptWritingFiles( properties, outputDirectory );
  		return properties;
  	}
docs: Processes user data that were already read.
  <p>
  This method handles the {@link #ENCODE_FILE_CONTENT_PREFIX} prefix.
  File contents are written on the disk and references are updated if necessary.
  </p>
  
  @param properties the user data as properties
  @param outputDirectory a directory into which files should be written
  <p>
  If null, files sent with {@link #ENCODE_FILE_CONTENT_PREFIX} will not be written.
  </p>
  
  @return a non-null object
  @throws IOException if something went wrong