diff --git a/api.java.classpath/src/org/netbeans/api/java/queries/SourceForBinaryQuery.java b/api.java.classpath/src/org/netbeans/api/java/queries/SourceForBinaryQuery.java
--- a/api.java.classpath/src/org/netbeans/api/java/queries/SourceForBinaryQuery.java
+++ b/api.java.classpath/src/org/netbeans/api/java/queries/SourceForBinaryQuery.java
@@ -46,6 +46,9 @@
 
 import java.net.URL;
 import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import javax.swing.event.ChangeEvent;
@@ -58,6 +61,8 @@
 import org.openide.util.ChangeSupport;
 import org.openide.util.Lookup;
 import org.openide.util.Parameters;
+import org.openide.util.RequestProcessor;
+import org.openide.util.RequestProcessor.Task;
 import org.openide.util.WeakListeners;
 
 /**
@@ -115,6 +120,22 @@
     public static Result2 findSourceRoots2 (URL binaryRoot) {
         // XXX as above, consider deleting
         SimplePathResourceImplementation.verify(binaryRoot, null);
+        Result2 r = foo(binaryRoot);
+
+        if (r != null) {
+            return r;
+        }
+
+        EmptyResultImpl eri = new EmptyResultImpl(binaryRoot);
+
+        emptyCache.put(binaryRoot, eri);
+
+        W.schedule(1000);
+            
+        return new Result2(eri);
+    }
+
+    private static Result2 foo(URL binaryRoot) {
         for (SourceForBinaryQueryImplementation impl : implementations.allInstances()) {
             Result2 result = null;
             if (impl instanceof SourceForBinaryQueryImplementation2) {
@@ -137,10 +158,75 @@
             }
         }
         LOG.log(Level.FINE, "findSourceRoots2({0}) -> nil", binaryRoot);
-        return EMPTY_RESULT2;
+        return null;
         
     }
 
+    private static final Map<URL, EmptyResultImpl> emptyCache = new HashMap<URL, EmptyResultImpl>();
+
+    private static final Task W = RequestProcessor.getDefault().create(new Runnable() {
+
+        @Override
+        public void run() {
+            for (EmptyResultImpl r : emptyCache.values()) r.update();
+            W.schedule(1000);
+        }
+    });
+
+    private static final class EmptyResultImpl implements SourceForBinaryQueryImplementation2.Result, ChangeListener {
+
+        private final ChangeSupport cs = new ChangeSupport(this);
+        private final AtomicReference<Result2> delegate = new AtomicReference<Result2>();
+        private final URL binaryRoot;
+
+        public EmptyResultImpl(URL binaryRoot) {
+            this.binaryRoot = binaryRoot;
+        }
+
+        @Override
+        public boolean preferSources() {
+            Result2 r = delegate.get();
+
+            if (r == null) return false;
+            return r.preferSources();
+        }
+
+        @Override
+        public FileObject[] getRoots() {
+            Result2 r = delegate.get();
+
+            if (r == null) return new FileObject[0];
+            return r.getRoots();
+        }
+
+        @Override
+        public void addChangeListener(ChangeListener l) {
+            cs.addChangeListener(l);
+        }
+
+        @Override
+        public void removeChangeListener(ChangeListener l) {
+            cs.removeChangeListener(l);
+        }
+
+        private void update() {
+            if (delegate.get() == null) {
+                Result2 r = foo(binaryRoot);
+
+                if (r != null) {
+                    delegate.set(r);
+                    r.addChangeListener(this);
+                    cs.fireChange();
+                }
+            }
+        }
+
+        @Override
+        public void stateChanged(ChangeEvent e) {
+            cs.fireChange();
+        }
+
+    }
     /**
      * Result of finding sources, encapsulating the answer as well as the
      * ability to listen to it.