title: Lucene prevent some fields to highlight
body: <p>Im having some trouble using the lucene highlighter. I have a record that holds three fields in my lucene indexes : title, content and classification(cls).</p>
  
  <p>When I search the indexes using "+(TITLE:test CONTENT:test) +CLS:dummy", I find the word "dummy" in title hits, it's my classification field and I don't want to highlight it. How do i avoid this ? </p>
  
  <p>Here is my test code : </p>
  
  <pre><code>    Directory directory = new RAMDirectory();
      StandardAnalyzer analyzer = new StandardAnalyzer(Version.LUCENE_36);
      IndexWriterConfig iwc = new IndexWriterConfig(Version.LUCENE_36, analyzer);
      IndexWriter iw = new IndexWriter(directory, iwc);
  
  
      //====================================write indexed======================================================
      Document document = new Document();
      Field _f_title = new Field("TITLE", "this is a test title - dummy",Field.Store.YES, Field.Index.ANALYZED);
      Field _f_content = new Field("CONTENT", "this is a test content",Field.Store.YES, Field.Index.ANALYZED);
      Field _f_cls = new Field("CLS", "dummy",Field.Store.YES, Field.Index.NOT_ANALYZED_NO_NORMS);
      document.add(_f_title);
      document.add(_f_content);
      document.add(_f_cls);
  
      iw.addDocument(document);
      iw.close();
      //====================================search indexed=====================================================
  
      SimpleHTMLFormatter htmlFormatter = new SimpleHTMLFormatter("&lt;span style='color:red;'&gt;", "&lt;/span&gt;");
      SimpleFragmenter fragmenter = new SimpleFragmenter(100);
      IndexReader ir = IndexReader.open(directory);
      IndexSearcher is = new IndexSearcher(ir);
      QueryParser parser = new QueryParser(Version.LUCENE_36, "", analyzer);
      Query query = parser.parse("+(TITLE:test CONTENT:test) +CLS:dummy");
      TopDocs docs = is.search(query, 10);
  
      Highlighter highlighter = new Highlighter(htmlFormatter, new QueryScorer(query));
      highlighter.setMaxDocCharsToAnalyze(Integer.MAX_VALUE);
      highlighter.setTextFragmenter(fragmenter);
  
      for(ScoreDoc cDoc : docs.scoreDocs) {
          Document _document = is.doc(cDoc.doc);
          System.out.println("title:" +  highlighter.getBestFragment(analyzer, "TITLE", _document.get("TITLE")));
          System.out.println("content:" +  highlighter.getBestFragment(analyzer, "CONTENT", _document.get("CONTENT")));
      }
      is.close();
  </code></pre>
  
  <p>This program output : </p>
  
  <pre><code>title:this is a &lt;span style='color:red;'&gt;test&lt;/span&gt; title - &lt;span style='color:red;'&gt;dummy&lt;/span&gt;
  content:this is a &lt;span style='color:red;'&gt;test&lt;/span&gt; content
  </code></pre>
  
  <p>Actually, I hope it's : </p>
  
  <pre><code>title:this is a &lt;span style='color:red;'&gt;test&lt;/span&gt; title - dummy
  content:this is a &lt;span style='color:red;'&gt;test&lt;/span&gt; content
  </code></pre>
  
  <p>What can I do?</p>