private static @Nullable String getPluginId(Module plugin) {
    final XmlFile pluginXml = PluginModuleType.getPluginXml(plugin);
    if (pluginXml == null) return null;

    final IdeaPlugin ideaPlugin = DescriptorUtil.getIdeaPlugin(pluginXml);
    return ideaPlugin == null ? null : ideaPlugin.getPluginId();
  }
private static @Nullable String getPluginId(Module plugin)