code: private String getLocalUsername(IceMediaStream stream) {
  		if (stream != null) {
  			if (stream.getRemotePassword() != null) {
  				return this.ufrag + ":" + stream.getRemotePassword();
  			}
  		}
  		return null;
  
  	}
docs: Returns the user name that the ICE Agent should use in connectivity
  checks for outgoing Binding Requests. According to RFC 5245, a Binding
  Request serving as a connectivity check MUST utilize the STUN short term
  credential mechanism. The username for the credential is formed by
  concatenating the username fragment provided by the peer with the
  username fragment of the agent sending the request, separated by a colon
  (":"). The password is equal to the password provided by the peer. For
  example, consider the case where agent L is the offerer, and agent R is
  the answerer. Agent L included a username fragment of LFRAG for its
  candidates, and a password of LPASS. Agent R provided a username fragment
  of RFRAG and a password of RPASS. A connectivity check from L to R (and
  its response of course) utilize the username RFRAG:LFRAG and a password
  of RPASS. A connectivity check from R to L (and its response) utilize the
  username LFRAG:RFRAG and a password of LPASS.
  
  @param media
  media name that we want to generate local username for.
  @return a user name that this <tt>Agent</tt> can use in connectivity
  check for outgoing Binding Requests.