RFR: 8284435: Add dedicated filler objects for known dead Java heap areas [v3]

[Thomas Schatzl]

On Fri, 29 Apr 2022 16:45:01 GMT, Ioi Lam <iklam at openjdk.org> wrote:

>> Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fix test
>
> The latest version looks good to me.

Thanks @iklam @walulyai for your reviews

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PR: https://git.openjdk.java.net/jdk/pull/8156