Add N&N entry for Multi-Release JAR compilation support in JDT 4.38

[Copilot]

This PR adds a comprehensive New and Noteworthy entry for the Eclipse JDT 4.38 release, documenting the new Multi-Release JAR compilation support feature.

Overview

JDT now provides native support for compiling Multi-Release JARs, allowing developers to maintain multiple versions of the same class compiled for different Java releases within a single project. This implementation follows the "Pattern 3: Single Project" approach and significantly simplifies the development workflow for libraries that need to support multiple Java versions.

Changes

Documentation Added

• N&N Entry: Added detailed entry in the Java Compiler section of news/4.38/jdt.md
• Screenshot: Included UI configuration dialog screenshot (multi-release-jar-config.png)

Entry Contents

The N&N entry covers:

• Introduction to Multi-Release JARs with reference to JEP 238
• Description of how JDT now supports native multi-release compilation
• Explanation of the Pattern 3: Single Project approach from the Maven Compiler Plugin documentation
• UI configuration instructions with screenshot
• Key capabilities:
  • Edit and compile Multi-Release Types simultaneously across different Java versions
  • Run Multi-Release compiled projects directly from the IDE
  • Automatic m2eclipse integration for maven-compiler-plugin executions
• Call for community feedback and testing

References Included

The entry properly references all related work:

• eclipse-jdt/eclipse.jdt.core#3900 - Core compilation support
• eclipse-jdt/eclipse.jdt.ui#2260 - UI support
• eclipse-jdt/eclipse.jdt.debug#753 - Debug/run support
• eclipse-m2e/m2e-core#2058 - Maven integration
• eclipse-jdt/eclipse.jdt.core#4275 - Feedback and known issues
• m2e-core release notes

Contributors

The entry credits:

• Christoph Laeubrich
• Stephan Herrmann

Compliance

This entry follows all N&N guidelines from instructions.md:

• Title in title case
• Active voice for better user engagement
• Backticks for UI elements and commands
• Screenshot with descriptive label
• PR/issue references included as HTML comments
• External documentation links provided
• Proper markdown formatting

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add a N&N entry for Eclipse JDT to promote the support of multi-release jar compilation</issue_title>
<issue_description>It should cover the topic of Native Multi Release Compilation support in JDT:

JDT now supports compilation of "Multi-Release-Types", that is the same class exits in different variants with the same name and can simultaneously be edited and compiled and automatically be placed in appropriate output folders.
It maps to an approach described as "Pattern 3: Single Project" described here https://maven.apache.org/plugins/maven-compiler-plugin/multirelease.html and as described in the "Challenges" section currently there is no good IDE support for that case, we solve this now by using the "highest" JDK and compile individual class files with the according release option.
The other patterns work, but they require a much more sophisticated setup in the IDEs and are usually not directly executable or requires a lot of custom configuration:

• e.g. here InteliJ https://blog.jetbrains.com/idea/2017/10/creating-multi-release-jar-files-in-intellij-idea/ and in the issue tracker https://youtrack.jetbrains.com/issue/IJPL-18554/Add-support-for-building-Java-9-multi-release-jars)
• Netbeans seem to support it through custom builds https://stackoverflow.com/questions/3161985/how-to-generate-multiple-jars-from-a-project-in-netbeans but it seems hard to find concrete information
• Maven generally supports it but is all on the commandline level: https://blog.bmarwell.de/2023/10/22/trickery-with-multi-release-jars.html

Now it becomes incredible simple when used with Eclipse IDE/JDT by just setting a simple option the classpath dialog of a source folder!

To promote this new feature we should write a good summary as a N&N entry;

• short introduction of Multi-Release Jars see https://openjdk.org/jeps/238 and how they are used
• describe we now can do multi-release compilation in JDT, so multi release types can exits in the same project in different source folders and are compiled according to the release, reference Add multi-release compilation support to JDT eclipse-jdt/eclipse.jdt.core#3900
• User can enable this through the UI, include a screenshot from Support configuration of the release for a a source folder eclipse-jdt/eclipse.jdt.ui#2260 (comment)), reference Support configuration of the release for a a source folder eclipse-jdt/eclipse.jdt.ui#2260
• Users can run Multi-Release compiled projects directly from the IDE, reference Support launching Multi-Release-Compiled Projects eclipse-jdt/eclipse.jdt.debug#753
• We still have some open issues and appreciate feedback and testing of this new feature, reference Mature support for multi-release projects eclipse-jdt/eclipse.jdt.core#4275
• m2eclipse has build in support now for mapping maven-compiler-plugin executions used for multi-release jars into JDT configuration, reference Add support for new JDT multi-release compilation eclipse-m2e/m2e-core#2058 and https://github.com/eclipse-m2e/m2e-core/blob/main/RELEASE_NOTES.md#multi-release-jar-support</issue_description>

<agent_instructions>We want to add a new N&N entry (see https://eclipse.dev/eclipse/markdown/?f=news/instructions.md for details) for the JDT project at the 4.38 release here: https://github.com/eclipse-platform/www.eclipse.org-eclipse/blob/master/news/4.38/jdt.md</agent_instructions>

Comments on the Issue (you are @copilot in this section)

Fixes #424

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[laeubi]

This looks like a quite good summary to me!