public static void merge(Directory srcIndexDir, Directory srcTaxDir,
Directory destIndexDir, Directory destTaxDir) throws IOException {
IndexWriter destIndexWriter = new IndexWriter(destIndexDir,
new IndexWriterConfig(ExampleUtils.EXAMPLE_VER, null));
DirectoryTaxonomyWriter destTaxWriter = new DirectoryTaxonomyWriter(destTaxDir);
merge(srcIndexDir, srcTaxDir, new MemoryOrdinalMap(), destIndexWriter, destTaxWriter);
destTaxWriter.close();
destIndexWriter.close();
}