Replace deprecated openjdk image with Microsoft OpenJDK

[Copilot]

Plan: Migrate from deprecated openjdk image to Microsoft OpenJDK

• Explore repository structure and identify openjdk usage
• Update Dockerfile.template to use mcr.microsoft.com/openjdk/jdk:21-ubuntu
• Revert unrelated package-lock.json changes
• Run linter to ensure changes are valid
• Verify the template file is properly updated
• Complete final review and security check

Summary

Successfully migrated the Java Dockerfile template from the deprecated openjdk:21-jdk-alpine image to the Microsoft OpenJDK image mcr.microsoft.com/openjdk/jdk:21-ubuntu.

Changes Made:

• Updated /resources/templates/java/Dockerfile.template to use the Microsoft OpenJDK base image
• Maintained Java version 21 for compatibility
• Changed from Alpine Linux to Ubuntu base
• Reverted unrelated package-lock.json changes per review feedback

Validation:

• ✅ Linter passed (npm run lint)
• ✅ Build successful (npm run build)
• ✅ CodeQL security check passed
• ✅ Code review completed

Security Summary:

No security vulnerabilities were introduced by this change. The migration to the Microsoft OpenJDK image provides a supported and maintained base image.

Original prompt

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This section details on the original issue you should resolve

<issue_title>openjdk image is deprecated</issue_title>
<issue_description>The openjdk image we use as a base for Java projects is deprecated. We should move to mcr.microsoft.com/openjdk/jdk:25-ubuntu or similar.</issue_description>

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

• Fixes openjdk image is deprecated #384

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