private int doHackyStorageLevelDetection(TaskMonitor monitor) {
		// dig through the files in the rootDir and see if there is anything
		// that looks like a level1 or level2 directory.
		if (containsPdbSymbolDirsWithFiles(rootDir)) {
			if (ALREADY_WARNED_ABOUT.add(rootDir)) {
				Msg.warn(this,
					"Symbol directory missing control files, guessing storage scheme as level 1: " +
						rootDir);
			}
			return 1;
		}
		File[] possibleLevel2SymbolDirs =
			list(rootDir, f -> f.isDirectory() && f.getName().length() == 2);
		for (File dir : possibleLevel2SymbolDirs) {
			if (containsPdbSymbolDirsWithFiles(dir)) {
				if (ALREADY_WARNED_ABOUT.add(rootDir)) {
					Msg.warn(this,
						"Symbol directory missing control files, guessing storage scheme as level 2: " +
							rootDir);
				}
				return 2;
			}
		}
		return 0;
	}
Non-task monitor variant of {@link #isValid(TaskMonitor)}.

@return boolean true if this is a valid symbol store
Ghidra/Features/PDB/src/main/java/pdb/symbolserver/LocalSymbolStore.java