RFR: 8346109: Create JDK taglet for additional preview notes

[Chen Liang]

On Tue, 8 Apr 2025 06:51:20 GMT, Hannes Wallnöfer <hannesw at openjdk.org> wrote:

>> make/jdk/src/classes/build/tools/taglet/PreviewNote.java line 112:
>> 
>>> 110:                             """);
>>> 111:                     return sb.toString();
>>> 112:                 } else {
>> 
>> What does this else block do? In what case can the JEP number be blank?
>
> The else block generates the closing tag for the note. As you see in the PR description, the tag syntax resembles HTML open/close tags. This is a compromise to be able to locate the note within the description (which isn't possible with block tags), and being able to use rich content in the note without being required to writing a dedicated tag parser and rendering code. (I also happen to find this syntax easier to read than a custom inline tag, which would require additional rules to separate meta data from note content.)

Such usage should be reflected in `testPreviewNoteTag`, which currently does not use it as open/close tags.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23395#discussion_r2033775847