8297984: Turn on warnings as errors for javadoc

[magicus]

For some reason, we never turned on -Werror for javadoc. It is high time to do so.

This PR also fixes a recent issue with the javadoc in JFR that caused a warning, and enables building of javadoc on GHA. (It takes about 3 minutes, as a separate build job.)

---

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Issue

• JDK-8297984: Turn on warnings as errors for javadoc

Reviewers

• Sergey Bylokhov (@mrserb - Reviewer) ⚠️ Review applies to 20bc7222
• Erik Joelsson (@erikj79 - Reviewer) ⚠️ Review applies to 20bc7222

Reviewing

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[openjdk]

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[mlbridge]

Webrevs

• 01: Full - Incremental (a48c8a85)
• 00: Full (20bc7222)

[mrserb]

LGTM

[openjdk]

@magicus This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8297984: Turn on warnings as errors for javadoc

Reviewed-by: serb, erikj

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 20 new commits pushed to the master branch:

• 227364d: 8297953: Fix several C2 IR matching tests for RISC-V
• 1370228: 8297941: Add override modifier in space.hpp
• 319faa5: 8296084: javax/swing/JSpinner/4788637/bug4788637.java fails intermittently on a VM
• b73363f: 8297686: JFR: Improve documentation of EventStream::onMetadata(Consumer)
• 1376f33: 8297911: Memory leak in JfrUpcalls::on_retransform
• 5c0ff26: 8291444: GHA builds/tests won't run manually if disabled from automatic running
• 6d0fbb2: 8297645: Drop the test/jdk/java/net/httpclient/reactivestreams-tck-tests/TckDriver.java test
• 687fd71: 8297549: RISC-V: Add support for Vector API vector load const operation
• d50015a: 8297715: RISC-V: C2: Use single-bit instructions from the Zbs extension
• 9bbcb54: 8297784: Optimize @stable field for Method.isCallerSensitive
• ... and 10 more: https://git.openjdk.org/jdk/compare/09629570f5d064dc2a5cd670de8d648156ac3991...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[erikj79]

If you would like to exercise the full-docs build in GHA, you could make that build depend on the linux-x64 build and set --with-build-jdk and --with-docs-reference-jdk to point to it. That's how we do it internally at Oracle.

[magicus]

If you would like to exercise the full-docs build in GHA, you could make that build depend on the linux-x64 build and set --with-build-jdk and --with-docs-reference-jdk to point to it.

Good point. I don't think it's worth it, though. Since the output is not saved but thrown away, we will just be wasting CPU cycles. The full docs graph generation is unlikely to start failing as a result of general changes in the code, only if some of the code that generates the graphs were to be changed, and such PRs can test this separately.

[magicus]

Since we do not do "apt install graphviz", configure will automatically determine that full docs is impossible. My intent were to keep it that way, since if for some reason "dot" were to be installed on the GHA image, then suddenly the build time would jump from 3 minutes to 60, so I wanted to make it clear that we never want this to happen.

However, I realize my comment might be misunderstood as if full docs is impossible to do without the cost of rebuilding everything. I'll see if I can clarify it without turning it into an essay about the reasoning.

[magicus]

/integrate

[openjdk]

Going to push as commit df07255.
Since your change was applied there have been 20 commits pushed to the master branch:

• 227364d: 8297953: Fix several C2 IR matching tests for RISC-V
• 1370228: 8297941: Add override modifier in space.hpp
• 319faa5: 8296084: javax/swing/JSpinner/4788637/bug4788637.java fails intermittently on a VM
• b73363f: 8297686: JFR: Improve documentation of EventStream::onMetadata(Consumer)
• 1376f33: 8297911: Memory leak in JfrUpcalls::on_retransform
• 5c0ff26: 8291444: GHA builds/tests won't run manually if disabled from automatic running
• 6d0fbb2: 8297645: Drop the test/jdk/java/net/httpclient/reactivestreams-tck-tests/TckDriver.java test
• 687fd71: 8297549: RISC-V: Add support for Vector API vector load const operation
• d50015a: 8297715: RISC-V: C2: Use single-bit instructions from the Zbs extension
• 9bbcb54: 8297784: Optimize @stable field for Method.isCallerSensitive
• ... and 10 more: https://git.openjdk.org/jdk/compare/09629570f5d064dc2a5cd670de8d648156ac3991...master

Your commit was automatically rebased without conflicts.

[openjdk]

@magicus Pushed as commit df07255.

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