@@ -50,5 +50,9 @@ class AssertingLeafCollector extends FilterLeafCollector {
     lastCollected = doc;
   }
 
+  @Override
+  public DocIdSetIterator filterIterator(DocIdSetIterator scorerIterator) {
+    return super.filterIterator(scorerIterator);
+  }
 }
 
/*
 * 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.lucene.search;

import java.io.IOException;

/** Wraps another Collector and checks that
 *  order is respected. */
class AssertingLeafCollector extends FilterLeafCollector {

  private final int min;
  private final int max;

  private Scorable scorer;
  private int lastCollected = -1;

  AssertingLeafCollector(LeafCollector collector, int min, int max) {
    super(collector);
    this.min = min;
    this.max = max;
  }

  @Override
  public void setScorer(Scorable scorer) throws IOException {
    this.scorer = scorer;
    super.setScorer(AssertingScorable.wrap(scorer));
  }

  @Override
  public void collect(int doc) throws IOException {
    assert doc > lastCollected : "Out of order : " + lastCollected + " " + doc;
    assert doc >= min : "Out of range: " + doc + " < " + min;
    assert doc < max : "Out of range: " + doc + " >= " + max;
    assert scorer.docID() == doc : "Collected: " + doc + " but scorer: " + scorer.docID();
    in.collect(doc);
    lastCollected = doc;
  }

}


Is this necessary?