How to Automatically Add Hashtag In Jetpack Publicize Plugin

JetPack has lot of great functions, one of my favourite is publicize that will auto post published WordPress posts into selected social media like Twitter, Facebook, Google+ etc.
You can modify the content of social post before publishing a post. But if you want to do it automatically, just add the following code somewhere in your plugin or functions.php file.

add_filter( 'wpas_default_message', 'auto_add_publicize_hashtag', 10, 4 );

function auto_add_publicize_hashtag($title) {
	$title = $title.' #hashtag1 #hashtag2';
	return $title;
}

Once it saved, you publicize screen will be like this: