RFR: 8316493: Make immutable maps @ValueBased [v3]

[Chen Liang]

On Fri, 22 Sep 2023 14:44:11 GMT, Glavo <duke at openjdk.org> wrote:

>> Per Minborg has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
>> 
>>  - Merge branch 'master' into vb-map2
>>  - Remove redundant impl spec parts
>>  - Merge pull request #4 from cl4es/HashMapViews
>>    
>>    Add simple HashMapViews microbenchmark
>>  - Add simple HashMapViews microbenchmark
>>  - Remove caching in AbstractMap and make immutable maps @ValueBased
>
> src/java.base/share/classes/java/util/AbstractMap.java line 524:
> 
>> 522:     protected Object clone() throws CloneNotSupportedException {
>> 523:         AbstractMap<?,?> result = (AbstractMap<?,?>)super.clone();
>> 524:         return result;
> 
> Suggestion:
> 
>         return super.clone();

Since this base class has no more fields, this method should probably be removed and its spec change included as part of the CSR.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15614#discussion_r1334536969