RFR: 8178355: IdentityHashMap uses identity-based comparison for values everywhere except remove(K,V) and replace(K,V,V)

[liach]

On Thu, 21 Apr 2022 00:48:00 GMT, Stuart Marks <smarks at openjdk.org> wrote:

>> Explicitly implement `remove` and `replace` in `IdentityHashMap` to compare values by identity. Updated API documentation of these two methods ([Preview](https://cr.openjdk.java.net/~liach/8178355/IdentityHashMap.html#remove(java.lang.Object,java.lang.Object))) to mention such behavior.
>
> Thanks for working on this. Yes I can review and sponsor this change.
> 
> Sorry I got a bit distracted. I started looking at the test here, and this lead me to inquire about what other tests we have for `IdentityHashMap`, and the answer is: not enough. See [JDK-8285295](https://bugs.openjdk.java.net/browse/JDK-8285295). (But that should be handled separately.)

@stuart-marks I have updated the tests to be based off that from [JDK-8285295](https://bugs.openjdk.java.net/browse/JDK-8285295). Anything else that needs an update?

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PR: https://git.openjdk.java.net/jdk/pull/8259