title: How can I send a private message to another user using android facebook sdk?
body: <p>I have searched on internet, but I have not found a solution for my problem. 
  In my app I have an option for a Facebook using the android Facebook <code>sdk</code>, then I get the information of user  <strong><em>Facebook(accessToken, userId)</em></strong> say <code>USER1</code>. Is there any way to send a private message to another user say <code>USER2</code> who is not a friend of <code>USER1</code>.</p>