private void rebuildDirectoryIndex(File dir) throws IOException {
		for (File f : dir.listFiles()) {
			if (f.isFile() && f.getName().endsWith(PROPERTY_EXT)) {
				try {
					if (!addFileToIndex(new IndexedPropertyFile(f))) {
						logRebuildError("Invalid item property file: " + f);
					}
				}
				catch (NotFoundException e) {
					logRebuildError("Item property file contains invalid parent path:" + f);
				}
			}
		}
	}
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