8388833: Fix JDWP spec w.r.t. setting static final fields and provide warnings about setting final fields

[plummercj]

The JDWP implementation (debug agent) allows the writing of static final fields and instance final fields. This has always been the case since no checks are made to prevent it, and JNI doesn't prevent it. The JDI spec forbids the setting of final fields, and it has a check that will throw an exception if attempted. However, it is important that we continue to allow JDWP to write final fields because some debuggers allow for it at the JDI level (protected by a click through warning). Although these debuggers are not fully JDI compliant, there is no requirement that they be compliant, so JDWP should continue to support this behavior. Much of this was discussed in the PR for JDK-8281652, which clarified in the JDI spec that writing final fields was not allowed. This was just a spec clarification. JDI already forbid the setting of final fields.

Having said all that, the JDWP spec for ClassType.SetValues says "Final fields cannot be set." This is clearly wrong as it has always been allowed. ObjectReference.SetValues says nothing about final fields, and also allows them to be set.

This PR has two spec updates:

• Get rid of the "Final fields cannot be set." text for ClassType.SetValues.
• ObjectReference.SetValues and ReferenceType.SetValues should warn against setting final fields by using language similar to JNI.

I've also updated two tests to test for setting both static final fields and instance final fields. The tests (before my changes) verified the setting of fields (not final) on the debuggee side. I tried the same with final fields and ran into problems. The compiler inlines final primitives values, so setting the final fields is not seen when the fields are referenced from java (or at least this was the case with static final fields. I'm not positive about instance final fields). So I added support for using GetValues to verify the results rather than relying on the debuggee's view of the fields.

Testing in progress.

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Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
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• Commit message must refer to an issue
• Change requires CSR request JDK-8389222 to be approved

Issues

• JDK-8388833: Fix JDWP spec w.r.t. setting static final fields and provide warnings about setting final fields (Bug - P4)
• JDK-8389222: Fix JDWP spec w.r.t. setting static final fields and provide warnings about setting final fields (CSR)

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[bridgekeeper]

👋 Welcome back cjplummer! 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]

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[openjdk]

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[plummercj]

/label remove core-libs

[openjdk]

@plummercj
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[mlbridge]

Webrevs

• 00: Full (aa71c226)

[AlanBateman]

Spec update looks good (and consistent with JNI as you note).

[plummercj]

/csr

[openjdk]

@plummercj has indicated that a compatibility and specification (CSR) request is needed for this pull request.

@plummercj please create a CSR request for issue JDK-8388833 with the correct fix version. This pull request cannot be integrated until the CSR request is approved.