Index: lucene/facet/src/java/org/apache/lucene/facet/index/DrillDownStream.java
===================================================================
--- lucene/facet/src/java/org/apache/lucene/facet/index/DrillDownStream.java	(revision 1561317)
+++ lucene/facet/src/java/org/apache/lucene/facet/index/DrillDownStream.java	(working copy)
@@ -1,7 +1,6 @@
 package org.apache.lucene.facet.index;
 
 import java.io.IOException;
-import java.util.Iterator;
 
 import org.apache.lucene.analysis.TokenStream;
 import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
@@ -33,7 +32,7 @@
 public class DrillDownStream extends TokenStream {
 
   private final FacetIndexingParams indexingParams;
-  private final Iterator<CategoryPath> categories;
+  private final Iterable<CategoryPath> categories;
   private final CharTermAttribute termAttribute;
   
   private CategoryPath current;
@@ -41,7 +40,7 @@
   
   public DrillDownStream(Iterable<CategoryPath> categories, FacetIndexingParams indexingParams) {
     termAttribute = addAttribute(CharTermAttribute.class);
-    this.categories = categories.iterator();
+    this.categories = categories;
     this.indexingParams = indexingParams;
   }
 
@@ -53,10 +52,10 @@
   @Override
   public final boolean incrementToken() throws IOException {
     if (current.length == 0) {
-      if (!categories.hasNext()) {
+      if (!categories.iterator().hasNext()) {
         return false; // no more categories
       }
-      current = categories.next();
+      current = categories.iterator().next();
       termAttribute.resizeBuffer(current.fullPathLength());
       isParent = false;
     }
@@ -75,7 +74,7 @@
 
   @Override
   public void reset() throws IOException {
-    current = categories.next();
+    current = categories.iterator().next();
     termAttribute.resizeBuffer(current.fullPathLength());
     isParent = false;
   }