}
        markCleanedUp();
    }

    private SortedSetMultimap<GradleVersion, VersionSpecificCacheDirectory> scanForVersionSpecificCacheDirs() {
        SortedSetMultimap<GradleVersion, VersionSpecificCacheDirectory> cacheDirsByBaseVersion = TreeMultimap.create();
        for (VersionSpecificCacheDirectory cacheDir : versionSpecificCacheDirectoryScanner.getExistingDirectories()) {

        then:
        directories as List == [
            new VersionSpecificCacheDirectory(cacheBaseDir.file("0.9-20101220110000+1100"), GradleVersion.version("0.9-20101220110000+1100")),
            new VersionSpecificCacheDirectory(cacheBaseDir.file("1.2.3-rc-1"), GradleVersion.version("1.2.3-rc-1")),
            new VersionSpecificCacheDirectory(cacheBaseDir.file("2.3.4"), GradleVersion.version("2.3.4"))
        ]
    }

    }

    @Override
    public SortedSet<GradleVersion> getUsedGradleVersions() {
        SortedSet<GradleVersion> result = new TreeSet<>();
        for (VersionSpecificCacheDirectory cacheDir : directoryScanner.getExistingDirectories()) {
            result.add(cacheDir.getVersion());
        }
        return result;
    }