RFR: 6766: Add heap usage before and after GC to the Garbage Collections table [v3]

[Marcus Hirt]

On Thu, 1 Oct 2020 19:30:12 GMT, Jean-Philippe Bempel <github.com+4610701+jpbempel at openjdk.org> wrote:

>> Columns are hidden for now
>> 
>> Here some screenshots of the changes:
>> 
>> ![JMC_UsedHeapBeforeAfterGC](https://user-images.githubusercontent.com/4610701/94465934-f030a300-01c0-11eb-8492-2b921f695833.png)
>> 
>> 
>> 
>> ![JMC_UsedHeapBeforeAfterGCColumns](https://user-images.githubusercontent.com/4610701/94465962-fc1c6500-01c0-11eb-8dc9-5b3346668381.png)
>
> Jean-Philippe Bempel has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix constant name for columns

Marked as reviewed by hirt (Lead).

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PR: https://git.openjdk.java.net/jmc/pull/112