[Nestmates] Add a core reflection API to get nestmate information

[Peter Levart]

Hi David,

On 11/16/2017 10:52 PM, David Holmes wrote:
>>> John prefers to minimize exceptions for the Java API. :)
>>
>> Suppose that this is basic reflection API to get nestmate information 
>> and that it will also be used for reflective access checks. For 
>> example in jdk.internal.reflect.Reflection#verifyMemberAccess, which 
>> is used 
>
> It isn't. The reflection API is purely for "external" use. Real access 
> checks are performed in the same way as the VM access checks - as 
> required - and will report the same exceptions in the same way.
>
> David 

Real access checks performed by bytecode(s), yes. But what about 
reflective access checks - those performed by Method.invoke, 
Field.[get|set], Constructor.newInstance? They will have to be revised 
some day to include the nestmates. What facility should those methods 
use to implement the checks (the guts of those checks is in 
jdk.internal.reflect.Reflection#verifyMemberAccess).

Is the plan to have special internal native methods to facilitate that? 
I don't quite understand why should a Class.isNestmateOf(Class) behave 
any differently than real VM access check.

Regards, Peter