493271 : fix NPE in OverlayConfigurator#mavenProjectChanged()

Change-Id: I2cc814945d01fcc6f7dde4e7177a243df2091af9
Signed-off-by: Fred Bricon <fbricon@gmail.com>
diff --git a/org.eclipse.m2e.wtp/src/org/eclipse/m2e/wtp/OverlayConfigurator.java b/org.eclipse.m2e.wtp/src/org/eclipse/m2e/wtp/OverlayConfigurator.java
index bb5927a..021af14 100644
--- a/org.eclipse.m2e.wtp/src/org/eclipse/m2e/wtp/OverlayConfigurator.java
+++ b/org.eclipse.m2e.wtp/src/org/eclipse/m2e/wtp/OverlayConfigurator.java
@@ -67,7 +67,7 @@
   private void mavenProjectChanged(IMavenProjectFacade facade, IProgressMonitor monitor) throws CoreException {
     if(facade == null) { return; }
     IProject project = facade.getProject();
-    if (WTPProjectsUtil.isM2eWtpDisabled(facade, monitor) || project.getResourceAttributes().isReadOnly()){
+    if (!project.isAccessible() || WTPProjectsUtil.isM2eWtpDisabled(facade, monitor) ||  project.getResourceAttributes() == null || project.getResourceAttributes().isReadOnly()){
       return;
     }