private static int getIndexVersion(String firstIndexLine) {
		int indexVersion = -1;
		if (firstIndexLine != null && firstIndexLine.length() != 0) {
			if (firstIndexLine.startsWith(INDEX_VERSION_PREFIX)) {
				String versionStr = firstIndexLine.substring(INDEX_VERSION_PREFIX.length());
				try {
					indexVersion = Integer.parseInt(versionStr);
				}
				catch (Exception e) {
					Msg.error(IndexedLocalFileSystem.class,
						"Invalid file-system version (" + versionStr + ")");
					indexVersion = Integer.MAX_VALUE;
				}
			}
			else {
				indexVersion = 0;
			}
		}
		return indexVersion;
	}
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