Force reconciling if a java project was touched

[laeubi]

What it does

If a classpath container changes, JDT "touches" the project resulting in a resource change being triggered. This is currently ignored by the JavaReconciler leading to possible wrong state displayed in an editor.

This now enhance the JavaReconciler to check for changed java projects if not already a reconciling was forced.

Fix #2074

How to test

see

• [4.35] On startup Java editor shows error annotations on valid code that don't always disappear eclipse-pde/eclipse.pde#1667 (comment)

Author checklist

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

[Phillipus]

Hi, I tested this PR using build I20250311-1800 and the simple test case from eclipse-pde/eclipse.pde#1667 (comment).

Unfortunately, I see the same behaviour. The first launch of child Eclipse debug is OK, but thereafter the error markers remain. There are a couple of times the markers clear, but mainly on each launch they remain red.

[laeubi]

It seems sometimes the flags are just zero ... but this is also the case for a normal resource change. So I'm a bit out of ideas how to detect that actually the classpath of the project was modified.

One can for example try it out by adding/removing a JUNIT classpath container. In this case it triggers a resource change with flags=0.

[laeubi]

@Phillipus just curious, can you try to create a second project?

If I look at org.eclipse.jdt.core.JavaCore.setClasspathContainer(IPath, IJavaProject[], IClasspathContainer[], IProgressMonitor) it has special handling for if there is only one project updated. and even though the API claims that

In reaction to changing container values, the JavaModel will be updated to reflect the new state of the updated container. A combined Java element delta will be notified to describe the corresponding classpath changes resulting from the container update.

I can't see that this happens it seems it only updates some internal maps...

[laeubi]

Closing as it does not seem the right way.

[Phillipus]

@Phillipus just curious, can you try to create a second project?

Yep, that makes a difference. I created a second project just the same as the first and the red markers do not appear, even momentarily.