RFR: JDK-8269401: Merge "Exceptions" and "Errors" into "Exception Classes" [v2]

[Jonathan Gibbons]

On Thu, 21 Oct 2021 12:30:42 GMT, Hannes Wallnöfer <hannesw at openjdk.org> wrote:

>> This is a conceptually simple change to merge the "Exception" and "Error" classes into a single "Exception Class" group.
>> 
>> The only change that is not strictly related to the merge is the removal of unused type subsets and related methods in `TypeElementCatalog.java` and the use of `Collections.emptySortedSet()` as the default return value in the `allClasses` method (I made sure it is never modified).
>
> Hannes Wallnöfer has updated the pull request incrementally with one additional commit since the last revision:
> 
>   JDK-8269401: Include Throwable in exception classes

Various internal comments about resource naming, for later, but for now, this code looks good.

I note that the new "policy" for merging these and calling them "Exception Classes" applies independently of the value of the `--release` option.  That's probably not wrong, and we can't maintain old and new forms to an unreasonable degree, but I just wanted to call it out as a change.

src/jdk.javadoc/share/classes/jdk/javadoc/internal/doclets/toolkit/util/TypeElementCatalog.java line 153:

> 151:         } else if (utils.isInterface(typeElement)) {
> 152:             addTypeElement(typeElement, interfaces);
> 153:         }

(This comment also applies to all related code in this class.)

Wow, good catch, if all those sets are really unused.

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Marked as reviewed by jjg (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/6061