code: private String[] getRequiredJarFilesInternal(final JobID id) {
  
  		final LibraryManagerEntry entry = this.libraryManagerEntries.get(id);
  
  		if (entry == null) {
  			return null;
  		}
  
  		return entry.getRequiredJarFiles();
  	}
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