RFR: 8328821: Map.of().entrySet() mutators should throw UnsupportedOperationException [v3]

[Chen Liang]

On Tue, 4 Jun 2024 17:42:23 GMT, Liam Miller-Cushon <cushon at openjdk.org> wrote:

>> This change overrides mutator methods in the implementation returned by `Map.of().entrySet()` to throw `UnsupportedOperationException`.
>
> Liam Miller-Cushon 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 six additional commits since the last revision:
> 
>  - Merge remote-tracking branch 'origin/master' into JDK-8328821-make-clear-consistent
>  - Check m.entrySet().hashCode() in MOAT
>  - Merge remote-tracking branch 'origin/master' into JDK-8328821-make-clear-consistent
>  - Use AbstractImmutableSet
>  - Throw UOE for all Map.of().entrySet() mutator methods
>  - 8328821: Make the ImmutableCollections clear() call consistent
>    
>    Without overriding clear(), a call to it in an empty map would
>    just return, as iterator.hasNext() would be false. However if
>    calling Map.of().clear() throws an exception. To make the
>    behavior of Map.of().entrySet().clear() consistent, we need to
>    have an implementation of clear() for the entry set that throws
>    as well.

test/jdk/java/util/Map/MapFactories.java line 505:

> 503: 
> 504:     @Test(expectedExceptions=UnsupportedOperationException.class)
> 505:     public void immutableEntrySetAddAllDisallowed() {

Looking back at MOAT, do you think we should add these into MOAT?
https://github.com/openjdk/jdk/blob/598af2e51464be089b64da4024e62865c2c6ec72/test/jdk/java/util/Collection/MOAT.java#L594-L619

We just need to add calls to `testMapMutatorsAlwaysThrow` and `testEmptyMapMutatorsAlwaysThrow` to check
`test(Empty)CollMutatorsAlwaysThrow(map.entrySet());`, `test(Empty)CollMutatorsAlwaysThrow(map.keySet());`, and `test(Empty)CollMutatorsAlwaysThrow(map.values());`

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PR Review Comment: https://git.openjdk.org/jdk/pull/18522#discussion_r1669279616