How can I use multiple hashtags on facebook

Question

I use fb.ui for sharing on facebook with a hashtag

FB.ui({
    method: 'share',
    href: url,
    hashtag: '#TestHash1'
}, function(response){
});

How can I send 2 hashtags? I tried each of the below, but they do not work.

hashtag: '#TestHash1#TestHash1'
hashtag: '#TestHash1 #TestHash1'
hashtag: ['#TestHash1', '#TestHash1']