2573: Support 2 reviewers by default for some areas of the JDK

[zhaosongzs]

There was a two-reviewers feature in Skara. We can configure two-reviewers labels in the configuration and if the PR contains one of the two-reviewers labels, when the PR is ready for integration, in the merge ready comment, skara would add a line "One or more changes in this pull request modifies files in areas of the source code that often require two reviewers. Please consider if this is the case for this pull request, and if so, await a second reviewer to approve this pull request before you integrate it." However, this feature was never used in production. It's only used in skara repo(e.g. #1761 (comment)), and I never noticed this message...
This PR is trying to make an improvement for this feature, when the PR contains two-reviewers label, the bot will automatically increase reviewers count to 2. Even when the label is removed later, the count won't be lowered back.
Also, the explicit "/reviewers" command will always win in this case.

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• I have successfully run sh gradlew test on macOS or Linux

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace

Issue

• SKARA-2573: Support 2 reviewers by default for some areas of the JDK (Enhancement - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/skara.git pull/1764/head:pull/1764
$ git checkout pull/1764

Update a local copy of the PR:
$ git checkout pull/1764
$ git pull https://git.openjdk.org/skara.git pull/1764/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 1764

View PR using the GUI difftool:
$ git pr show -t 1764

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/skara/pull/1764.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back zsong! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[kevinrushforth]

Will we be able to take advantage of this for jfx? We don't have any labels for different code areas, so I'd want to be able to configure Skara to always default to 2 reviewers for the main jfx repo, allowing for /reviewers 1 to lower it back down.

[zhaosongzs]

Will we be able to take advantage of this for jfx? We don't have any labels for different code areas, so I'd want to be able to configure Skara to always default to 2 reviewers for the main jfx repo, allowing for /reviewers 1 to lower it back down.

Yes, we can configure 'rfr' as the two-reviewers label for jfx repo.

[mlbridge]

Webrevs

• 01: Full - Incremental (034e4ea2)
• 00: Full (c9f75af7)

[erikj79]

I don't think this is correct. The common "2 reviewers" requirement in various part of the JDK is, at least as far as I understand it, equivalent to /reviewers 2, not /reviewers 2 reviewer. So the required additional reviewer does not need the project role "Reviewer". I think this call will result in requiring two reviews from role reviewer. I think it would be correct to just change "reviewers" to "authors", but I'm not 100% sure.

Suggested change

	var marker = ReviewersTracker.setReviewersMarker(2, "reviewers");
	var marker = ReviewersTracker.setReviewersMarker(2, "authors");

[zhaosongzs]

maybe @kevinrushforth can answer this question.

I am ok to change it to authors, at least 1 reviewer will be required, so it only affects the requirement of second reviewer's role.

[kevinrushforth]

Erik is right. The expectation is that it is equivalent to /reviewers 2 which would be 1 reviewers and 1 author or higher.