// Copyright (C) 2010 The Android Open Source Project
//
// Licensed 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 com.google.gerrit.server.config;

import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.Multimap;

import org.eclipse.jgit.revwalk.FooterLine;

import java.util.List;
import java.util.regex.Matcher;

public class TrackingFooters {
  protected List<TrackingFooter> trackingFooters;

  public TrackingFooters (final List<TrackingFooter> trFooters) {
    trackingFooters = trFooters;
  }

  public List<TrackingFooter> getTrackingFooters() {
    return trackingFooters;
  }

  public boolean isEmpty() {
    return trackingFooters.isEmpty();
  }

  public Multimap<String, String> extract(List<FooterLine> lines) {
    Multimap<String, String> r = ArrayListMultimap.create();
    for (FooterLine footer : lines) {
      for (TrackingFooter config : trackingFooters) {
        if (footer.matches(config.footerKey())) {
          Matcher m = config.match().matcher(footer.getValue());
          while (m.find()) {
            String id = m.groupCount() > 0
                ? m.group(1)
                : m.group();
            if (!id.isEmpty()) {
              r.put(config.system(), id);
            }
          }
        }
      }
    }
    return r;
  }
}

@@ -1310,24 +1310,72 @@
 p.create();%0A
+    if (lines == null) %7B%0A      return r;%0A    %7D%0A%0A
     for (Foo

Protect the TrackingFooters.extract from null input parameter