RFR: 8257776: [valhalla:jep390] Add disclaimer about future changes to value-based classes [v2]

[Dan Smith]

On Fri, 4 Dec 2020 21:49:07 GMT, Mandy Chung <mchung at openjdk.org> wrote:

>> Dan Smith has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Rephrase "future release" warning.
>
> src/jdk.incubator.foreign/share/classes/jdk/incubator/foreign/MemoryAddress.java line 44:
> 
>> 42:  * All implementations of this interface must be <a href="{@docRoot}/java.base/java/lang/doc-files/ValueBased.html">value-based</a>;
>> 43:  * programmers should treat instances that are {@linkplain #equals(Object) equal} as interchangeable and should not
>> 44:  * use instances for synchronization, or unpredictable behavior may occur. For example, in a future release, synchronization may fail.
> 
> Nit: this line is very long and maybe good to wrap this line and the line above..   I understand that the javadoc in this file has long lines and href is an outliner.

Yeah, it's not conventional, but it's the style in this file, so I decided not to perturb it. This is an incubator module, I assume it will get polished up before becoming final.

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PR: https://git.openjdk.java.net/valhalla/pull/294