return perRepoGuard.guardByKey(repository.getUniqueId(), new Supplier<File>() {
            @Nullable
            @Override
            public File get() {
                File workingDir = inMemoryCache.getWorkingDirForSelector(repository, selector.getVersionConstraint());
                if (workingDir == null) {
                    workingDir = delegate.selectVersion(selector, repository);
                    if (workingDir == null) {

        String cacheKey = versionCacheKey(repository, version);
        checkoutDirs.put(cacheKey, dir);
    }

    @Nullable
    public File getWorkingDirForSelector(VersionControlRepositoryConnection repository, VersionConstraint constraint) {
        String cacheKey = constraintCacheKey(repository, constraint);
        return resolvedVersions.get(cacheKey);
    }