code: private ClassLoader getClassLoaderInternal(final JobID id) {
  
  		final LibraryManagerEntry entry = this.libraryManagerEntries.get(id);
  
  		if (entry == null) {
  			return null;
  		}
  
  		return entry.getClassLoader();
  	}
docs: Returns the class loader to the specified vertex.
  
  @param id
  the ID of the job to return the class loader for
  @return the class loader of requested vertex or <code>null</code> if no class loader has been registered with the
  given ID.
  @throws IOException
  thrown if the library cache manager could not be instantiated