import com.google.gerrit.extensions.annotations.Listen; //导入依赖的package包/类
private void scan() throws InvalidPluginException {
  Map<Class<? extends Annotation>, Iterable<ExtensionMetaData>> extensions =
      scanner.scan(pluginName, Arrays.asList(Export.class, Listen.class));
  for (ExtensionMetaData export : extensions.get(Export.class)) {
    export(export);
  }
  for (ExtensionMetaData listener : extensions.get(Listen.class)) {
    listen(listener);
  }
  if (env.hasHttpModule()) {
    exportInitJs();
  }
}