Fix IllegalArgumentException in getFolder() for ancestor resource dirs

When a resource <directory> resolves to an ancestor of the project
(e.g.,  from a child module, or
<directory>..</directory>), projectLocation.relativize(folderPath)
produces '..'. Then project.getFolder('..') normalizes to IPath '/',
triggering IllegalArgumentException: Path must include project and
resource name: /.

Add a guard to detect when the relativized path starts with '..' and
return the project, so the caller (addResourceDirs) skips the resource
directory. This follows the same pattern as the existing
workaround.

Fixes #1790

Signed-off-by: Changyong Gong <chagon@microsoft.com>

Author: chagong

org.eclipse.m2e.jdt/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %Bundle-Name
 Bundle-SymbolicName: org.eclipse.m2e.jdt;singleton:=true
-Bundle-Version: 2.5.100.qualifier
+Bundle-Version: 2.5.200.qualifier
 Bundle-Localization: plugin
 Export-Package: org.eclipse.m2e.jdt,
  org.eclipse.m2e.jdt.internal;x-friends:="org.eclipse.m2e.jdt.ui",

org.eclipse.m2e.jdt/src/org/eclipse/m2e/jdt/internal/AbstractJavaProjectConfigurator.java

@@ -1003,7 +1003,14 @@ protected IContainer getFolder(IProject project, String path) throws CoreExcepti
     }
     if(!project.exists(relativePath) && Files.exists(folderPath)
         && !ResourcesPlugin.getWorkspace().getRoot().getLocation().toPath().equals(folderPath)) {
-      String linkName = projectLocation.relativize(folderPath).toString().replace("/", "_");
+      Path relativized = projectLocation.relativize(folderPath);
+      if(relativized.startsWith("..")) {
+        // Resource directory is outside (ancestor or sibling of) the project.
+        // Cannot create a valid linked folder for paths that escape the project tree.
+        // Return the project itself so the caller skips this resource directory.
+        return project;
+      }
+      String linkName = relativized.toString().replace("/", "_");
       IFolder folder = project.getFolder(linkName);
       createLinkWithRetry(folder, folderPath.toUri());
       folder.setPersistentProperty(LINKED_MAVEN_RESOURCE, "true");