Java editor error marker without compile errors

Observed during experiments for #723.

To reproduce:

1. Import projects from attached archive: [JavaEditorCompileErrorBugzip.zip](https://github.com/eclipse-jdt/eclipse.jdt.core/files/10714766/JavaEditorCompileErrorBugzip.zip)
2. Open source file `Test1.java`
3. Observe error marker in the Java editor: `The method test2(null) is undefined for the type Test2`
4. Observe there are no actual compile errors / error markers listed in the `Problems` view.
5. Clean and build the workspace (main menu -> Project -> "Clean...").
6. Run `Test1` as Java application, observe it runs fine.

The Java editor error marker is shown when `TestLibraryUnnamedModule.jar` is exported from the classpath of project `Test2`.