LUCENE-5129: CategoryAssociationsContainer should not allow null associations

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1506526 13f79535-47bb-0310-9956-ffa450edef68

lucene/CHANGES.txt

@@ -84,6 +84,10 @@ API Changes
   searchAfter exceeds the number of documents in the reader. 
   (Crocket via Shai Erera)
 
+* LUCENE-5129: CategoryAssociationsContainer no longer supports null
+  association values for categories. If you want to index categories without
+  associations, you should add them using FacetFields. (Shai Erera)
+  
 Optimizations
 
 * LUCENE-5088: Added TermFilter to filter docs by a specific term.

lucene/facet/src/java/org/apache/lucene/facet/associations/AssociationsListBuilder.java

@@ -54,13 +54,6 @@ public class AssociationsListBuilder implements CategoryListBuilder {
       // build per-association key BytesRef
       CategoryAssociation association = associations.getAssociation(cp);
       
-      if (association == null) {
-        // it is ok to set a null association for a category - it's treated as a
-        // regular category in that case.
-        ++idx;
-        continue;
-      }
-
       BytesRef bytes = res.get(association.getCategoryListID());
       if (bytes == null) {
         bytes = new BytesRef(32);

lucene/facet/src/java/org/apache/lucene/facet/associations/CategoryAssociationsContainer.java

@@ -30,11 +30,12 @@ public class CategoryAssociationsContainer implements Iterable<CategoryPath> {
   
   /**
    * Adds the {@link CategoryAssociation} for the given {@link CategoryPath
-   * category}. Overrides any assocation that was previously set. It is ok to
-   * pass {@code null}, in which case the category will be treated as a regular
-   * one (i.e. without association value).
+   * category}. Overrides any assocation that was previously set.
    */
   public void setAssociation(CategoryPath category, CategoryAssociation association) {
+    if (association == null) {
+      throw new IllegalArgumentException("cannot set a null association to a category");
+    }
     categoryAssociations.put(category, association);
   }