Integrated: 8317620: Build JDK tools with ModuleMainClass attribute

[Mandy Chung]

On Wed, 1 Nov 2023 19:58:07 GMT, Mandy Chung <mchung at openjdk.org> wrote:

> Tool modules can be created via `jmod --main-class` option such that `ModuleMainClass` attribute will be added in `module-info.class` and the module's main class can be launched via `java -m <module-name>` without specifying the name of the main class.
> 
> In addition, for modules with `ModuleMainClass` attribute, jlink will pre-resolve the module graph such that when such module is launched at runtime (without `--add-modules` or `--limit-modules` option), the runtime can skip the module resolution and speed up the startup time.
> 
> This PR extends the build system to allow a module to specify the main class under `make/modules/$MODULE/Jmod.gmk` file.    Also JDK tools with a single entry point (or a primary entry point) are candidates to add `ModuleMainClass` attribute in `module-info.class` to benefit from the jlink optimization.   For example, `java -m jdk.jpackage` will be launched using the pre-resolved module graph.
> 
> Verified manually by running `java -m $MODULE` on the modules with main class.

This pull request has now been integrated.

Changeset: 008ca2a7
Author:    Mandy Chung <mchung at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/008ca2a72587f1518199e81f6f7ec7fbdc258d99
Stats:     17 lines in 8 files changed: 6 ins; 0 del; 11 mod

8317620: Build JDK tools with ModuleMainClass attribute

Reviewed-by: erikj, alanb

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PR: https://git.openjdk.org/jdk/pull/16463