private void Export(string rootPath)
{
if (rootPath == null) {
throw new ArgumentNullException("rootPath");
}
if (!Directory.Exists(rootPath)) {
throw new ArgumentException("Specified directory doesn't exist.");
}
// export files
RootFolder.Export(rootPath);
// export .nuspec file
ExportManifest(Path.Combine(rootPath, PackageMetadata.Id + ".nuspec"));
}