allow subclass to perform additional action.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@3700 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/triggers/Trigger.java

@@ -110,7 +110,7 @@ public abstract class Trigger<J extends Item> implements Describable<Trigger<?>>
         return spec;
     }
 
-    private Object readResolve() throws ObjectStreamException {
+    protected Object readResolve() throws ObjectStreamException {
         try {
             tabs = CronTabList.create(spec);
         } catch (ANTLRException e) {