Unicode collation support.
  Collation
  converts each token into its binary CollationKey using the 
  provided Collator, allowing it to be stored as an index term.
  // "fa" Locale is not supported by Sun JDK 1.4 or 1.5
  Collator collator = Collator.getInstance(new Locale("ar"));
  CollationKeyAnalyzer analyzer = new CollationKeyAnalyzer(version, collator);
  RAMDirectory ramDir = new RAMDirectory();
  IndexWriter writer = new IndexWriter(ramDir, new IndexWriterConfig(version, analyzer));
  Document doc = new Document();
  doc.add(new TextField("content", "\u0633\u0627\u0628", Field.Store.YES));
  writer.addDocument(doc);
  writer.close();
  IndexReader ir = DirectoryReader.open(ramDir);
  IndexSearcher is = new IndexSearcher(ir);
  QueryParser aqp = new QueryParser(version, "content", analyzer);
  aqp.setAnalyzeRangeTerms(true);
    
  // Unicode order would include U+0633 in [ U+062F - U+0698 ], but Farsi
  // orders the U+0698 character before the U+0633 character, so the single
  // indexed Term above should NOT be returned by a ConstantScoreRangeQuery
  // with a Farsi Collator (or an Arabic one for the case when Farsi is not
  // supported).
  ScoreDoc[] result
    = is.search(aqp.parse("[ \u062F TO \u0698 ]"), null, 1000).scoreDocs;
  assertEquals("The index Term should not be included.", 0, result.length);
  Analyzer analyzer 
    = new CollationKeyAnalyzer(version, Collator.getInstance(new Locale("da", "dk")));
  RAMDirectory indexStore = new RAMDirectory();
  IndexWriter writer = new IndexWriter(indexStore, new IndexWriterConfig(version, analyzer));
  String[] tracer = new String[] { "A", "B", "C", "D", "E" };
  String[] data = new String[] { "HAT", "HUT", "H\u00C5T", "H\u00D8T", "HOT" };
  String[] sortedTracerOrder = new String[] { "A", "E", "B", "D", "C" };
  for (int i = 0 ; i < data.length ; ++i) {
    Document doc = new Document();
    doc.add(new StoredField("tracer", tracer[i]));
    doc.add(new TextField("contents", data[i], Field.Store.NO));
    writer.addDocument(doc);
  }
  writer.close();
  IndexReader ir = DirectoryReader.open(indexStore);
  IndexSearcher searcher = new IndexSearcher(ir);
  Sort sort = new Sort();
  sort.setSort(new SortField("contents", SortField.STRING));
  Query query = new MatchAllDocsQuery();
  ScoreDoc[] result = searcher.search(query, null, 1000, sort).scoreDocs;
  for (int i = 0 ; i < result.length ; ++i) {
    Document doc = searcher.doc(result[i].doc);
    assertEquals(sortedTracerOrder[i], doc.getValues("tracer")[0]);
  }
  Collator collator = Collator.getInstance(new Locale("tr", "TR"));
  collator.setStrength(Collator.PRIMARY);
  Analyzer analyzer = new CollationKeyAnalyzer(version, collator);
  RAMDirectory ramDir = new RAMDirectory();
  IndexWriter writer = new IndexWriter(ramDir, new IndexWriterConfig(version, analyzer));
  Document doc = new Document();
  doc.add(new TextField("contents", "DIGY", Field.Store.NO));
  writer.addDocument(doc);
  writer.close();
  IndexReader ir = DirectoryReader.open(ramDir);
  IndexSearcher is = new IndexSearcher(ir);
  QueryParser parser = new QueryParser(version, "contents", analyzer);
  Query query = parser.parse("d\u0131gy");   // U+0131: dotless i
  ScoreDoc[] result = is.search(query, null, 1000).scoreDocs;
  assertEquals("The index Term should be included.", 1, result.length);
  WARNING: Make sure you use exactly the same 
  Collator at index and query time -- CollationKeys
  are only comparable when produced by
  the same Collator.  Since {@link java.text.RuleBasedCollator}s
  are not independently versioned, it is unsafe to search against stored
  CollationKeys unless the following are exactly the same (best 
  practice is to store this information with the index and check that they
  remain the same at query time):
  ICUCollationKeyAnalyzer, available in the icu analysis module,
  uses ICU4J's Collator, which 
  makes its version available, thus allowing collation to be versioned
  independently from the JVM.  ICUCollationKeyAnalyzer is also 
  significantly faster and generates significantly shorter keys than 
  CollationKeyAnalyzer.  See
  http://site.icu-project.org/charts/collation-icu4j-sun for key
  generation timing and key length comparisons between ICU4J and
  java.text.Collator over several languages.
  CollationKeys generated by java.text.Collators are 
  not compatible with those those generated by ICU Collators.  Specifically, if
  you use CollationKeyAnalyzer to generate index terms, do not use
  ICUCollationKeyAnalyzer on the query side, or vice versa.