code: public static String[] getRequiredJarFiles(final JobID id) throws IOException {
  
  		if (id == null) {
  			return new String[0];
  		}
  
  		final LibraryCacheManager lib = get();
  
  		return lib.getRequiredJarFilesInternal(id);
  	}
docs: Returns the names of the required libraries of the specified job.
  
  @param id
  the ID of the job to return the names of required libraries for.
  @return the names of the required libraries or <code>null</code> if the specified job ID is unknown
  @throws IOException
  thrown if the library cache manager could not be instantiated