Print warning if adding parent folder of library to the classpath #4797

[fedejeanne]

What it does

Print a warning in the trace log if the Class-Path entry in the manifest file of a third-party library includes a parent folder. This might not be forbidden but it's a dangerous practice.

Contributes to: #4797

How to test

• Launch the Runtime Workspace, making sure that tracing is enabled like this:

• Import the 2 projects in this ZIP: projects.zip
• Restart the application

Expected

This should appear in the Console output:

| main | 2026-02-03 14:26:33.814 | org.eclipse.jdt.core | /debug | org.eclipse.jdt.internal.core.ClasspathEntry | resolvedChainedLibraries | 993 | WARN: Classpath entry ../ in manifest of jar file: \a\lib\badlib.jar references a parent folder. This may cause issues like: https://github.com/eclipse-jdt/eclipse.jdt.core/issues/4797 |

Author checklist

• I have thoroughly tested my changes
• The change is following the coding conventions
• I have signed the Eclipse Contributor Agreement (ECA)

[fedejeanne]

@iloveeclipse I know you said you are busy in the next few weeks but maybe you could still make some time to take a look at this PR? It is pretty small and it merely adds a warning when some 3rd-party library does something risky like adding a parent folder to the classpath (which, as you said yourself in #4797 (comment), is a PITA). That way we could at least identify such bad libraries and handle them better.

Thank you in advance!