RFR: 8256156: JFR: Allow 'jfr' tool to show metadata without a recording

[Yang Yi]

On Fri, 5 Feb 2021 11:50:15 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

>> Hi @egahlin, thanks for your update. I have changed my patch according to the latest specification. Please help review this PR.
>> 
>> Thanks,
>> Yang Yi
>
> Now --events operates on types, not just events.
> 
> I think you could keep EventType, and much of the code that you changed into Type. You just need to check if a type is an EventType, i.e. if (Type.SUPER_TYPE_EVENT.equals(type.getSuperType())) { ...}, when using --events (or --categories).

I've updated my patch. Only when meeting an event type, a filter applied, otherwise it operates on types

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PR: https://git.openjdk.java.net/jdk/pull/1904