text: public IndexInput openInput(String name, IOContext context) throws IOException {ensureOpen();final String id = IndexFileNames.stripSegmentName(name);final FileEntry entry = entries.get(id);if (entry == null) {String datFileName = IndexFileNames.segmentFileName(segmentName, "", Lucene50CompoundFormat.DATA_EXTENSION);throw new FileNotFoundException("No sub-file with id " + id + " found in compound file \"" + datFileName + "\" (fileName=" + name + " files: " + entries.keySet() + ")");}return handle.slice(name, entry.offset, entry.length);}