RFR: 8254622: Hide superclasses from conditionally exported packages

[Chen Liang]

On Fri, 4 Apr 2025 13:36:19 GMT, Hannes Wallnöfer <hannesw at openjdk.org> wrote:

> Please review an enhancement to treat classes and interfaces that are not included and not unconditionally exported as hidden. This means they do not show up in the generated documentation even if they are implemented or extended by a documented type. 
> 
> This change makes the `@hidden` JavaDoc tag unnecessary in two internal base classes that previously used it, `jdk.internal.vm.vector.VectorSupport` and `jdk.internal.event.Event`. The generated documentation is unchanged.
> 
> The change also adds support for the `@hidden` JavaDoc tag in interfaces, which was previously missing, and adds coverage to `TestHiddenTag.java`.

src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/formats/html/Signatures.java line 165:

> 163:                     for (TypeMirror type : interfaces) {
> 164:                         TypeElement tDoc = utils.asTypeElement(type);
> 165:                         if (!(utils.isPublic(tDoc) || utils.isLinkable(tDoc)) || utils.isHidden(tDoc)) {

This `(!isPublicOrProtected && !isLinkable) || isHidden` trio appears a few times. The conditions are negated and wrapped in parentheses so it is easily confusing on the web; can we extract this check into a new utils method?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24446#discussion_r2029581822