RFR 8213400: Support choosing curve name in keytool keypair generation

[Weijun Wang]

Thanks. Please also take a look at the release note at https://bugs.openjdk.java.net/browse/JDK-8213821.

--Max

> On Nov 13, 2018, at 11:02 PM, Adam Petcher <adam.petcher at oracle.com> wrote:
> 
> This change looks good to me. Thanks.
>