docs.add(createDocument("ab", "a"));
docs.add(createDocument("a", "b"));
docs.add(createDocument("abcd", "c"));
docs.add(createDocument("abc", "d"));
DirectoryManager dirMgr = new RAMDirectoryManager();
PersistentIndex idx = new PersistentIndex("index",
new StandardAnalyzer(Version.LUCENE_36), Similarity.getDefault(),
new DocNumberCache(100),
new IndexingQueue(new IndexingQueueStore(new RAMDirectory())),