<span class="paramLabel">Parameters:</span></dt>
<dd><code>addr</code> - InetAddress of the host.  may be null.</dd>
<dd><code>port</code> - the port on the host</dd>
<dd><code>protocol</code> - protocol scheme (e.g. imap, pop3, etc.)</dd>
<dd><code>prompt</code> - any additional String to show as part of
                          the prompt; may be null.</dd>
<dd><code>defaultUserName</code> - the default username. may be null.</dd>
<dt><span class="returnLabel">Returns:</span></dt>
<dd>the authentication 