@Nullable
  public static String getBuildNumber(String ideaHome) {
    try {
      @NonNls final String buildTxt = SystemInfo.isMac ? "Resources/build.txt" : "build.txt";
      File file = new File(ideaHome, buildTxt);
      if (SystemInfo.isMac && !file.exists()) {
        // IntelliJ IDEA 13 and earlier used a different location for build.txt on Mac;
        // recognize the old location as well
        file = new File(ideaHome, "build.txt");
      }
      return FileUtil.loadFile(file).trim();
    }
    catch (IOException e) {
      return null;
    }
  }
@Nullable
  public static String getBuildNumber(String ideaHome)