public static @Nullable String checksum(@Nullable MavenProject project) {
    if (null == project) return null;

    Model pom = project.getModel();
    cleanModel(pom);

    StringWriter sWriter = new StringWriter();
    MavenXpp3Writer pomWriter = new MavenXpp3Writer();
    try {
      pomWriter.write(sWriter, pom);
    }
    catch (IOException e) {
      return null;
    }

    return ChecksumUtil.checksum(sWriter.toString());
  }
public static @Nullable String checksum(@Nullable MavenProject project)