I can reproduce this problem in main method only.

Like:
public class Main {
    public static void main(String[] args) {
        System.out.println("sdgadfgad"); // breakpoint here
        System.out.println("dfgdsfhrshen");
    }
    
}

If I put breakpoint to some other place it works!
public class Main {
    public Main() {
        System.out.println("dfgsdhhgfgh"); // breakpoint here
    }
    public static void main(String[] args) {
        new Main ();
    }
    
}

Confirm, please...

Yes, it is true. I forgot to mention that it breaks the commit
validation suite. That's why I signed it as P1.

Looks like problem is caused by src hierarchy.

This piece of code:

        DataObject dataObject = getDataObject (url);
        if (dataObject == null) return null;
        SourceCookie.Editor sc = (SourceCookie.Editor)
dataObject.getCookie 
            (SourceCookie.Editor.class);
        if (sc == null) return null;
        StyledDocument sd = null;
        try {
            sd = sc.openDocument ();
        } catch (IOException ex) {
        }
        if (sd == null) return null;
        int offset = NbDocument.findLineOffset (sd, lineNumber);
        Element element = sc.findElement (offset);

returns SourceElement in place of MethodElement!

Fixed.

*** This issue has been marked as a duplicate of 50591 ***

Verified.

Reorganization of java component