Index: src/test/groovy/GroovyMethodsTest.groovy
===================================================================
--- src/test/groovy/GroovyMethodsTest.groovy	(revision 15221)
+++ src/test/groovy/GroovyMethodsTest.groovy	Wed Feb 04 23:13:39 EST 2009
@@ -720,7 +720,7 @@
         assert x.sum() == 10
         assert x.size() == 4
         assert x.class == WackyList
-        def y = x.findAll{ it % 2 == 1 }
+        def y = x.findAll{ it % 2 == 1 } as WackyList
         assert y.size() == 2
         assert y.class == WackyList
     }
Index: src/test/groovy/vm5/GroovyMethodsTest.groovy
===================================================================
--- src/test/groovy/vm5/GroovyMethodsTest.groovy	(revision 15221)
+++ src/test/groovy/vm5/GroovyMethodsTest.groovy	Wed Feb 04 23:17:57 EST 2009
@@ -92,10 +92,10 @@
         def q = [1, 2, 3, 4, 5, 6, 7, 8, 9] as LinkedBlockingQueue
         assert q.size() == 9
         assert q.class == LinkedBlockingQueue
-        q += 10
+        q = (q + 10) as LinkedBlockingQueue
         assert q.size() == 10
         assert q.class == LinkedBlockingQueue
-        def r = q.findAll{ it % 2 == 0 }
+        def r = q.findAll{ it % 2 == 0 } as LinkedBlockingQueue
         assert r.size() == 5
         assert r.class == LinkedBlockingQueue
         def s = ((r as LinkedList) - [4, 6]) as LinkedBlockingQueue
Index: src/main/org/codehaus/groovy/runtime/DefaultGroovyMethodsSupport.java
===================================================================
--- src/main/org/codehaus/groovy/runtime/DefaultGroovyMethodsSupport.java	(revision 15221)
+++ src/main/org/codehaus/groovy/runtime/DefaultGroovyMethodsSupport.java	Wed Feb 04 16:01:30 EST 2009
@@ -115,8 +115,6 @@
     protected static Collection cloneSimilarCollection(Collection orig, int newCapacity) {
         Collection answer = (Collection) cloneObject(orig);
         if (answer != null) return answer;
-        answer = cloneCollectionFromClass(orig);
-        if (answer != null) return answer;
 
         // fall back to creation
         answer = createSimilarCollection(orig, newCapacity);
@@ -153,9 +151,6 @@
         if (orig instanceof List) {
             return createSimilarList((List) orig, newCapacity);
         }
-        Collection answer = createCollectionFromClass(orig);
-        if (answer != null) return answer;
-
         if (orig instanceof Queue) {
             return new LinkedList();
         }
@@ -163,26 +158,19 @@
     }
 
     protected static List createSimilarList(List orig, int newCapacity) {
-        List answer = (List) createCollectionFromClass(orig);
-        if (answer != null) return answer;
-
         if (orig instanceof LinkedList) {
-            answer = new LinkedList();
-        } else if (orig instanceof Stack) {
-            answer = new Stack();
-        } else if (orig instanceof Vector) {
-            answer = new Vector();
-        } else {
-            answer = new ArrayList(newCapacity);
+            return new LinkedList();
         }
-        return answer;
+        if (orig instanceof Stack) {
+            return new Stack();
-    }
+        }
+        if (orig instanceof Vector) {
+            return new Vector();
+        }
+        return new ArrayList(newCapacity);
+    }
 
     protected static Set createSimilarSet(Set orig) {
-        Set answer = (Set) createCollectionFromClass(orig);
-        if (answer != null) return answer;
-
-        // fall back to some defaults
         if (orig instanceof SortedSet) {
             return new TreeSet();
         }
@@ -193,10 +181,6 @@
     }
 
     protected static Map createSimilarMap(Map orig) {
-        Map answer = createMapFromClass(orig);
-        if (answer != null) return answer;
-
-        // fall back to some defaults
         if (orig instanceof SortedMap) {
             return new TreeMap();
         }
@@ -209,75 +193,9 @@
         return new LinkedHashMap();
     }
 
-    private static Collection createCollectionFromClass(Collection orig) {
-        if (orig instanceof AbstractCollection) {
-            try {
-                final Constructor constructor = orig.getClass().getConstructor();
-                return (Collection) constructor.newInstance();
-            } catch (Exception e) {
-                // ignore
-            }
-        }
-        return null;
-    }
-
-    private static Collection cloneCollectionFromClass(Collection orig) {
-        if (orig instanceof AbstractCollection) {
-			try {
-				final Constructor constructor = orig.getClass().getConstructor(Collection.class);
-				return (Collection) constructor.newInstance(orig);
-			} catch (Exception e) {
-				// ignore
-			}
-			try {
-				final Constructor constructor = orig.getClass().getConstructor();
-				final Collection result = (Collection) constructor.newInstance();
-				result.addAll(orig);
-				return result;
-			} catch (Exception e) {
-				// ignore
-			}
-		}
-        return null;
-    }
-
-    private static Map createMapFromClass(Map orig) {
-        if ((orig instanceof AbstractMap) || (orig instanceof Hashtable)) {
-            try {
-                final Constructor constructor = orig.getClass().getConstructor();
-                return (Map) constructor.newInstance();
-            } catch (Exception e) {
-                // ignore
-            }
-        }
-        return null;
-    }
-
-    private static Map cloneMapFromClass(Map orig) {
-        if ((orig instanceof AbstractMap) || (orig instanceof Hashtable)) {
-			try {
-				final Constructor constructor = orig.getClass().getConstructor(Map.class);
-				return (Map) constructor.newInstance(orig);
-			} catch (Exception e) {
-				// ignore
-			}
-			try {
-				final Constructor constructor = orig.getClass().getConstructor();
-				final Map result = (Map) constructor.newInstance();
-				result.putAll(orig);
-				return result;
-			} catch (Exception e) {
-				// ignore
-			}
-		}
-        return null;
-    }
-
     protected static Map cloneSimilarMap(Map orig) {
         Map answer = (Map) cloneObject(orig);
         if (answer != null) return answer;
-        answer = cloneMapFromClass(orig);
-        if (answer != null) return answer;
 
         // fall back to some defaults
         if (orig instanceof TreeMap)