in src/main/java/com/googlesource/gerrit/plugins/hooks/TopicEdited.java [34:47]
  public void onTopicEdited(TopicEditedListener.Event event) {
    HookArgs args = hookFactory.createArgs();
    ChangeInfo c = event.getChange();
    args.add("--change", c.id);
    args.add("--change-owner", c.owner);
    args.add("--project", c.project);
    args.add("--branch", c.branch);
    args.add("--changer", event.getWho());
    args.add("--old-topic", event.getOldTopic());
    args.add("--new-topic", event.getChange().topic);
    hook.execute(c.project, args);
  }