I think that moving last operator to the beginning of the next line is a good practice. That way you know right away the purpose of the second line, even it doesn't start with an operator. I also recommend 2 indentation spaces (2 tabs) for a previously broken tab, to differ it from the normal indentation. That is immediately visible as continuing previous line. Therefore I suggest this:
private static final Map<Class<? extends Persistent>, PersistentHelper> class2helper
= new HashMap<Class<? extends Persistent>, PersistentHelper>();