RFR 8202708, Add a check of opening stream for not-existing UNC url

[Roger Riggs]

Hi Felix,

Looks fine

Roger


On 5/11/18 6:15 AM, Felix Yang wrote:
> Hi all,
>
>    please review a change to add additional checking for opening 
> stream with not-existing UNC url.
>
> Bug:
>
>     https://bugs.openjdk.java.net/browse/JDK-8202708
>
> Webrev:
>
>     http://cr.openjdk.java.net/~xiaofeya/8202708/webrev.00/
>
> Thanks,
>
> Felix
>