RFR: JDK-8263507: Improve structure of package summary pages [v3]

[Hannes Wallnöfer]

On Mon, 19 Apr 2021 09:45:27 GMT, Hannes Wallnöfer <hannesw at openjdk.org> wrote:

>> This adds a feature to add sub-navigation links to the package summary page, but ended up more like a refactoring of the code to generate sub-navigation links. The reason for this is that generation of these links was highly idiosyncratic. Every writer class that wanted to create sub-nav links deposited something of itself in the `Navigation` instance which was then responsible for generating these links. The new code introduces a `Navigation.SubNavLinks` interface that allows writers to provide a list of links into their page content.
>> 
>> As for the new feature in the package summary page itself, I chose an approach that is a bit different from the one we use for other types of pages. Instead of displaying the inactive label instead of the link when a section is not present on the page, only the active links are displayed. The reason for this is that the package summary page contains so many potential summary tables that the sub-nav area gets quite crowded if they are all shown. Just showing the actually present pieces looked better to me.
>> 
>> Like in other sub-nav sections, the link labels sometimes use abbreviated terms such as "RELATED" instead of "RELATED PACKAGES" and "ENUMS" instead of "ENUM CLASSES". The full list of potential package sub-nav links is as follows:
>> 
>>     Package: Description | Related | Interfaces | Classes | Enums | Records | Exceptions | Errors | Annotations
>> 
>> An important implementation note is that I moved the code to compute package summary contents from `PackageSummaryBuilder` to `PackageWriterImpl`. The reason for this is that the contents are required to determine which links to create, and I didn't want to re-compute this information that was previously computed on the fly in the builder class. The various summary items are now stored in collection fields in the writer class. 
>> 
>> I have tried to add all the new properties and constants in a sensible place, which usually means alphabetic order within the sub-group of related entries.
>> 
>> I chose to keep the markup structure of the package summary page mostly unchanged, adding only `id` attributes to the existing `<li>` elements for each summary table. I decided against adding `class` attributes as well as it seems very unlikely to me that somebody would want to apply different styles to the various summary tables. Even without them, it could be done using the `id`s.
>
> Hannes Wallnöfer has updated the pull request incrementally with one additional commit since the last revision:
> 
>   JDK-8263507: Update JBS summary

I opted for doing the summary table merge within this same PR. I couldn't find an existing JBS issue for it, and splitting the work into two changesets and reverse their order seemed like a non-trivial amount of work.

I have updated the JBS summary to "Improve structure of package summary pages" to reflect the broader scope.

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PR: https://git.openjdk.java.net/jdk/pull/3413