JDK 11 RFR of 8202334: Update javax.lang.model.util visitors for 11

[joe darcy]

Hello,

Please review the webrev and CSR for 8202334: "Update 
javax.lang.model.util visitors for 11":

     http://cr.openjdk.java.net/~darcy/8202334.0/
     https://bugs.openjdk.java.net/browse/JDK-8202335

 From the CSR:

> The `javax.lang.model` API was added in Java SE 6. In each of Java SE 
> 7, 8, and 9, new sets of utility visitors were added for each release, 
> for example starting with `AbstractElementVisitor6`, types 
> `AbstractElementVisitor7`, `AbstractElementVisitor8`, 
> `AbstractElementVisitor8` were added in SE 7 and 8, respectively. 
> Similar patterns were followed for `ElementKindVisitor6`, and the rest 
> of the utility visitors.
>
> In Java SE 10, there were no language changes requiring new 
> operational behavior from the root visitors. Therefore, rather than 
> introducing yet another slate of visitor classes, the 9-era visitors 
> were updated to indicate they are appropriate for 10 as well 
> (CCC-8193194).
>
> In the absence of language changes in 11 which would require new 
> operational behavior from the visitors, the 9-era visitors should be 
> updated to indicate they are appropriate for releases 9 through 11.
>
> Solution
> --------
> Update the specification and `SupportedSourceVersion` annotations on 
> the 9-era visitor classes to indicate they are appropriate for release 11.

Thanks,

-Joe