title: File transfer in group chat with XMPP
body: <p>I am using group chat with open fire.</p>
  
  <p>i can able to send messages but how to send file to group with Smack library.</p>
  
  <p>i can able to send file to single user with below but i don't know how  to send to group chat (MUC) so all users in room will receive that file</p>
  
  <pre><code>OutgoingFileTransfer transfer = manager.createOutgoingFileTransfer("usre2@myHost/Smack");
  </code></pre>