diff -r 80b660cf4880 masterfs/src/org/netbeans/modules/masterfs/ProvidedExtensionsProxy.java
--- a/masterfs/src/org/netbeans/modules/masterfs/ProvidedExtensionsProxy.java	Tue Feb 17 00:25:26 2009 +0300
+++ b/masterfs/src/org/netbeans/modules/masterfs/ProvidedExtensionsProxy.java	Tue Feb 17 15:59:13 2009 +0100
@@ -45,6 +45,7 @@
 import java.io.IOException;
 import java.util.Collection;
 import java.util.Iterator;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import org.netbeans.modules.masterfs.providers.AnnotationProvider;
@@ -58,7 +59,7 @@
  * @author Radek Matous
  */
 public class ProvidedExtensionsProxy extends ProvidedExtensions {
-    private Collection/*AnnotationProvider*/ annotationProviders;
+    private Collection<AnnotationProvider> annotationProviders;
     private static ThreadLocal  reentrantCheck = new ThreadLocal();
     
     /** Creates a new instance of ProvidedExtensionsProxy */
@@ -247,7 +248,24 @@
                 });                
             }
         }
-    }        
+    }
+
+    @Override
+    public Object getAttribute(final File file, final String attrName) {
+        final AtomicReference<Object> value = new AtomicReference();
+        for (AnnotationProvider provider : annotationProviders) {
+            final InterceptionListener iListener = (provider != null) ? provider.getInterceptionListener() : null;
+            if (iListener instanceof ProvidedExtensions) {
+                runCheckCode(new Runnable() {
+                    public void run() {
+                        value.set(((ProvidedExtensions) iListener).getAttribute(file, attrName));
+                    }
+                });
+            }
+            if(value.get() != null) break;
+        }
+        return value.get();
+    }
     
     public static void checkReentrancy() {
         if (reentrantCheck.get() != null) {            
diff -r 80b660cf4880 masterfs/src/org/netbeans/modules/masterfs/filebasedfs/fileobjects/BaseFileObj.java
--- a/masterfs/src/org/netbeans/modules/masterfs/filebasedfs/fileobjects/BaseFileObj.java	Tue Feb 17 00:25:26 2009 +0300
+++ b/masterfs/src/org/netbeans/modules/masterfs/filebasedfs/fileobjects/BaseFileObj.java	Tue Feb 17 15:59:13 2009 +0100
@@ -358,8 +358,12 @@
             }
         } else if (attrName.equals("ExistsParentNoPublicAPI")) {
             return getExistingParent() != null;
-        } 
-                
+        } else if (attrName.startsWith("ProvidedExtensions")) {  //NOI18N
+            // #158600 - delegate to ProvidedExtensions if attrName starts with ProvidedExtensions prefix
+            ProvidedExtensions extension = getProvidedExtensions();
+            return extension.getAttribute(getFileName().getFile(), attrName);
+        }
+   
         return BaseFileObj.attribs.readAttribute(getFileName().getFile().getAbsolutePath().replace('\\', '/'), attrName);//NOI18N
     }
 
diff -r 80b660cf4880 masterfs/src/org/netbeans/modules/masterfs/providers/ProvidedExtensions.java
--- a/masterfs/src/org/netbeans/modules/masterfs/providers/ProvidedExtensions.java	Tue Feb 17 00:25:26 2009 +0300
+++ b/masterfs/src/org/netbeans/modules/masterfs/providers/ProvidedExtensions.java	Tue Feb 17 15:59:13 2009 +0100
@@ -175,5 +175,16 @@
      * @param fo file which <code>FileLock</code> was released
      * @since 1.11
      */                
-    public void fileUnlocked(FileObject fo) {}        
+    public void fileUnlocked(FileObject fo) {}
+
+    /**
+     * Called by {@code MasterFileSystem} when {@code FileObject} is
+     * queried for attribute and attribute's name starts with {@code ProvidedExtensions}
+     * prefix.
+     * @param attrName name of attribute
+     * @return value of attribute
+     */
+    public Object getAttribute(File file, String attrName) {
+        return null;
+    }
 }