517028: ResourceException below CollectMissingNaturesVisitor.visit (thrown in Project.checkAccessible)

Bug: 517028
Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=517028
diff --git a/org.eclipse.epp.mpc.ui/src/org/eclipse/epp/internal/mpc/ui/discovery/CollectMissingNaturesVisitor.java b/org.eclipse.epp.mpc.ui/src/org/eclipse/epp/internal/mpc/ui/discovery/CollectMissingNaturesVisitor.java
index 83c097b..0c2a893 100644
--- a/org.eclipse.epp.mpc.ui/src/org/eclipse/epp/internal/mpc/ui/discovery/CollectMissingNaturesVisitor.java
+++ b/org.eclipse.epp.mpc.ui/src/org/eclipse/epp/internal/mpc/ui/discovery/CollectMissingNaturesVisitor.java
@@ -24,9 +24,8 @@
 	private final Set<String> missingNatures = new HashSet<String>();
 
 	public boolean visit(IResourceDelta delta) throws CoreException {
-		if (delta.getResource().getType() == IResource.ROOT || (delta.getResource().getType() == IResource.PROJECT
-				&& ((IProject) delta.getResource()).isAccessible())) {
-			return true;
+		if (delta.getResource().getType() == IResource.ROOT || delta.getResource().getType() == IResource.PROJECT) {
+			return delta.getResource().isAccessible();
 		}
 		if (delta.getResource().getType() == IResource.FILE
 				&& IProjectDescription.DESCRIPTION_FILE_NAME