It seems no need to get a write lock under Spreadsheet#renderProperties(), which is a side effect from ZSS-618.

And ZSS-618 seems to be fixed in a wrong way to get a lock for ModelEventDispatcher.java as well.

In this ZSS-618 case, we should only get a lock to protect CellImpl#evalFormula() only for multi-threading and change the synchronized to use a write lock instead to boost performance for ZSS-618.