ProblemTextFilter cache is not atomic across its two fields #127

getFilters() keeps the cache in two separate volatile fields (cachedRawFilterList, cachedFilters) and updates them one after the other. A concurrent caller can therefore get a filter list that was parsed from a different raw string than the one it checked against.

This cannot happen today: the only caller (DocumentMarkupModelScanner) always runs on the EDT. It becomes a real bug as soon as isFiltered is called from another thread, for example a background scan or parallel tests (see #126).

Proposed fix: keep one immutable holder record Cache(String raw, List<Predicate<String>> filters) in a single volatile field and replace it in one write.