update javadoc for init(TokenStream) return

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@800849 13f79535-47bb-0310-9956-ffa450edef68

contrib/highlighter/src/java/org/apache/lucene/search/highlight/Scorer.java

@@ -32,7 +32,10 @@ public interface Scorer {
    * getTokenScore().
    * 
    * @param tokenStream
-   * @throws IOException 
+   * @return either a TokenStream that the Highlighter should continue using (eg
+   *         if you read the tokenSream in this method) or null to continue
+   *         using the same TokenStream that was passed in.
+   * @throws IOException
    */
   public TokenStream init(TokenStream tokenStream) throws IOException;