RFR: JDK-8310502 : Optimization for j.l.Long.fastUUID() [v26]

[温绍锦]

On Tue, 27 Jun 2023 16:12:50 GMT, 温绍锦 <duke at openjdk.org> wrote:

>>> Sadly, jdk.internal.util is exported to other modules so it does need to be looked at from an integrity perspective.
>> 
>> This is indeed a problem to consider.
>> 
>> Maybe we can move this array back into `HexDigits`. Then we create a new package `jdk.internal.digits` and move `Digits`, `DecimalDigits`, `HexDigits`, `OctalDigits` all into it.
>
> Hex256 has been moved to jdk.internal.digits, jdk.internal.digits is not exported.

now it's reuse the field of java.util.HexDigits#DIGITS

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PR Review Comment: https://git.openjdk.org/jdk/pull/14578#discussion_r1246156442