public static int readIndexVersion(String rootPath) throws IOException {
		File indexFile = new File(rootPath, INDEX_FILE);
		BufferedReader indexReader = null;
		try {
			indexReader = new BufferedReader(new InputStreamReader(
				new BufferedInputStream(new FileInputStream(indexFile)), "UTF8"));
			return getIndexVersion(indexReader.readLine());
		}
		finally {
			if (indexReader != null) {
				try {
					indexReader.close();
				}
				catch (IOException e) {
					// ignore
				}
			}
		}
	}
Attempt to parse index version
@param firstIndexLine
@return index version or -1 if index version unknown
Ghidra/Framework/FileSystem/src/main/java/ghidra/framework/store/local/IndexedLocalFileSystem.java