SOLR-8871 - adjusted header positioning

lucene/classification/src/java/org/apache/lucene/classification/KNearestNeighborClassifier.java

@@ -195,9 +195,10 @@ public class KNearestNeighborClassifier implements Classifier<BytesRef> {
     Map<BytesRef, Double> classBoosts = new HashMap<>(); // this is a boost based on class ranking positions in topDocs
     float maxScore = topDocs.getMaxScore();
     for (ScoreDoc scoreDoc : topDocs.scoreDocs) {
-      IndexableField storableField = indexSearcher.doc(scoreDoc.doc).getField(classFieldName);
+      IndexableField[] storableFields = indexSearcher.doc(scoreDoc.doc).getFields(classFieldName);
-      if (storableField != null) {
+      for (IndexableField singleStorableField : storableFields) {
-        BytesRef cl = new BytesRef(storableField.stringValue());
+        if (singleStorableField != null) {
+          BytesRef cl = new BytesRef(singleStorableField.stringValue());
         //update count
         Integer count = classCounts.get(cl);
         if (count != null) {
@@ -213,6 +214,7 @@ public class KNearestNeighborClassifier implements Classifier<BytesRef> {
         } else {
           classBoosts.put(cl, singleBoost);
         }
+        }
       }
     }
     List<ClassificationResult<BytesRef>> returnList = new ArrayList<>();

lucene/classification/src/java/org/apache/lucene/classification/document/KNearestNeighborDocumentClassifier.java

@@ -109,6 +109,7 @@ public class KNearestNeighborDocumentClassifier extends KNearestNeighborClassifi
     TopDocs knnResults = knnSearch(document);
     List<ClassificationResult<BytesRef>> assignedClasses = buildListFromTopDocs(knnResults);
     Collections.sort(assignedClasses);
+    max = Math.min(max, assignedClasses.size());
     return assignedClasses.subList(0, max);
   }
 
@@ -130,15 +131,14 @@ public class KNearestNeighborDocumentClassifier extends KNearestNeighborClassifi
         boost = field2boost[1];
       }
       String[] fieldValues = document.getValues(fieldName);
+      mlt.setBoost(true); // we want always to use the boost coming from TF * IDF of the term
       if (boost != null) {
-        mlt.setBoost(true);
+        mlt.setBoostFactor(Float.parseFloat(boost)); // this is an additional multiplicative boost coming from the field boost
-        mlt.setBoostFactor(Float.parseFloat(boost));
       }
       mlt.setAnalyzer(field2analyzer.get(fieldName));
       for (String fieldContent : fieldValues) {
         mltQuery.add(new BooleanClause(mlt.like(fieldName, new StringReader(fieldContent)), BooleanClause.Occur.SHOULD));
       }
-      mlt.setBoost(false);
     }
     Query classFieldQuery = new WildcardQuery(new Term(classFieldName, "*"));
     mltQuery.add(new BooleanClause(classFieldQuery, BooleanClause.Occur.MUST));

solr/core/src/test/org/apache/solr/update/processor/ClassificationUpdateProcessorTest.java

@@ -1,3 +1,19 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.apache.solr.update.processor;
 
 import java.io.IOException;
@@ -24,23 +40,6 @@ import org.junit.Test;
 import static org.hamcrest.core.Is.is;
 import static org.mockito.Mockito.mock;
 
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
 /**
  * Tests for {@link ClassificationUpdateProcessor}
  */