RFR: 8302818: Optimize wrapper sets and immutable sets of Enums [v7]

[Chen Liang]

On Wed, 22 Mar 2023 14:23:45 GMT, ExE Boss <duke at openjdk.org> wrote:

>> Tingjun Yuan has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix a whitespace error
>
> src/java.base/share/classes/java/util/ImmutableCollections.java line 1212:
> 
>> 1210:                 if (unseen == 0)
>> 1211:                     throw new NoSuchElementException();
>> 1212:                 lastReturned = unseen & -unseen;
> 
> Suggestion:
> 
>                 long lastReturned = unseen & -unseen;

Suggestion:

                long lastReturned = Long.lowestOneBit(unseen);

More descriptive. Same for below.

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PR Review Comment: https://git.openjdk.org/jdk/pull/12498#discussion_r1145005398