allow the replacement of non-serializable objects.

src/main/java/org/apache/ode/jacob/vpu/ExecutionQueueImpl.java

diff --git a/src/main/java/org/apache/ode/jacob/vpu/ExecutionQueueImpl.java b/src/main/java/org/apache/ode/jacob/vpu/ExecutionQueueImpl.java
index 42393f8..ce872fa 100644
--- a/src/main/java/org/apache/ode/jacob/vpu/ExecutionQueueImpl.java
+++ b/src/main/java/org/apache/ode/jacob/vpu/ExecutionQueueImpl.java
@@ -641,8 +641,9 @@
          * @throws IOException
          */
         protected Object replaceObject(Object obj) throws IOException {
-            if (!Serializable.class.isAssignableFrom(obj.getClass())) {
-                throw new IllegalArgumentException("Cannot replace non Serializable instance of " + obj.getClass());
+            if (!Serializable.class.isAssignableFrom(obj.getClass()) &&
+                    !(_replacementMap != null && _replacementMap.isReplaceable(obj))) {
+                throw new IllegalArgumentException("Cannot replace non-serializable or non-replacable instance of " + obj.getClass());
             }
 
             if (obj instanceof org.apache.ode.jacob.oo.ChannelProxy) {