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

[Chen Liang]

On Wed, 27 Mar 2024 17:36:28 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`.

src/java.base/share/classes/java/util/ImmutableCollections.java line 1321:

> 1319:                 }
> 1320: 
> 1321:                 // all mutating methods throw UnsupportedOperationException

Can we change this anonymous class to `return new AbstractImmutableSet<>` and override `hashCode` with `MapN.this.hashCode()`?

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PR Review Comment: https://git.openjdk.org/jdk/pull/18522#discussion_r1542086980