default.xml 这个文件有什么特点呢？
就是没有配置任何参数
安东尼给了一段描述，摘录如下：
Let it be known that this user can register without a password but since we do not assign
this user a user_context and we don't authenticate this user they will be put in context 'public'.
This isn't a security issue as the endpoint would be put into the same context 'public' as the
sofia profile that starts on 5080 by default. If you're paranoid just remove this file and
remove the external profile also.
If you're this paranoid you might wanna go buy some more tinfoil and disconnect from the internets.
Cuz we all know the internets is for pr0n anyway.
是不是很俏皮？