8146298: (dc spec) connect and disconnect methods should specify that they may block

[Brian Burkhalter]

For the issue [1] to improve the specification of DatagramChannel please review this doc change [2]. Hopefully I’ve captured the behavior accurately. Note the class-level doc change to match SocketChannel.

Thanks,

Brian

[1] https://bugs.openjdk.java.net/browse/JDK-8146298
[2] http://cr.openjdk.java.net/~bpb/8146298/webrev.00/