diff -r 1c999569643b -r acf2c31e22d4 samples/consistency/src-api2.0/api/Lookup.java
--- a/samples/consistency/src-api2.0/api/Lookup.java	Sat Jun 14 10:04:51 2008 +0200
+++ b/samples/consistency/src-api2.0/api/Lookup.java	Sat Jun 14 10:04:53 2008 +0200
@@ -1,6 +1,11 @@
 package api;
 
+import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
 import java.util.Set;
 
 /** Simplified version of NetBeans 
@@ -13,26 +18,49 @@
  * @version 2.0
  */
 // BEGIN: design.consistency.2.0
-public final class Lookup {
+public abstract class Lookup {
+    /** only for classes in the same package */
     Lookup() {
     }
     
     // BEGIN: design.consistency.lookup.2.0
     public <T> T lookup(Class<T> clazz) {
-        return null;
+        Iterator<T> it = doLookup(clazz);
+        return it.hasNext() ? it.next() : null;
     }
     // END: design.consistency.lookup.2.0
 
     // BEGIN: design.consistency.lookupAll.2.0
     public <T> Collection<? extends T> lookupAll(Class<T> clazz) {
-        return null;
+        Iterator<T> it = doLookup(clazz);
+        if (!it.hasNext()) {
+            return Collections.emptyList();
+        } else {
+            List<T> result = new ArrayList<T>();
+            while (it.hasNext()) {
+                result.add(it.next());
+            }
+            return result;
+        }
     }
     // END: design.consistency.lookupAll.2.0
 
     // BEGIN: design.consistency.lookupAllClasses.2.0
     public <T> Set<Class<? extends T>> lookupAllClasses(Class<T> clazz) {
-        return null;
+        Iterator<T> it = doLookup(clazz);
+        if (!it.hasNext()) {
+            return Collections.emptySet();
+        } else {
+            Set<Class<? extends T>> result = 
+                new HashSet<Class<? extends T>>();
+            while (it.hasNext()) {
+                result.add(it.next().getClass().asSubclass(clazz));
+            }
+            return result;
+        }
     }
     // END: design.consistency.lookupAllClasses.2.0
+// FINISH: design.consistency.2.0
+    
+    abstract <T> Iterator<T> doLookup(Class<T> clazz);
 }
-// END: design.consistency.2.0
\ No newline at end of file