public String getUsername() {
        return username;
    }
Returns the username used to connect to the SMTP server. If the username
is {@code null}, no username will be used when connecting to the server.

@return the username used to connect to the SMTP server, or {@code null} if
     there is no username.
xmppserver/src/main/java/org/jivesoftware/util/EmailService.java