[MJAVADOC-796] Do not follow links for Java 12+

[jira-importer]

Michael Osipov opened MJAVADOC-796 and commented

For years, we have been following redirects manually because javadoc was not able to. with Java 12 (JDK-8190312) is was implemented and our logic can be skipped when javadoc 12+ is used.

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Affects: 3.7.0

Issue Links:

• MJAVADOC-656 Following redirects breaks valid links
  ("is required by")

Remote Links:

• GitHub Pull Request #287
  
• Fixed in JDK-8190312
  

[jira-importer]

Phillip Webb commented

A big +1 for this change because there is a subtle difference with the way that the JDK follows links and the way that Maven does. With JDK, the links are resolved when loading the data, but the original link is left unchanged in the generated HTML. With Maven the link is actually changed in the HTML.

You can see one example of the problem this causes in spring-projects/spring-boot#40998

[jira-importer]

Michael Osipov commented

It is a shame that the redirect code in Javadoc has never been backported to 8 and 11.

[jira-importer]

Michael Osipov commented

Phillip Webb, can you also provide a reference to the described behavior?

[jira-importer]

Michael Osipov commented

Fixed with aa0a6662452c219d2b1d04be224a2a17e19c6a3d.

[jira-importer]

Phillip Webb commented

Phillip Webb, can you also provide a reference to the described behavior?

I was going by this commit. If you look at the new open method it gets given the URL, follows any redirects and then returns an InputStream. I'm reading that method as the thing that opens the URL and returns the content. Note that it doesn't return a new URL, so the original link must be left as it was.

[jira-importer]

Michael Osipov commented

Alright, that is exactly the spot I have found as well. Unfortunately, the only thing we can do is to follow the element-list/package-list redirect and pass on the redirected parent resource. This can work, but not always. We cannot retain the original URL because that would make old Javadoc versions fail again. Tough situation. I dare to say that current logic is more or less pointless in this plugin.