adding no-op instance that's convenient sometimes

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@17358 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/model/Saveable.java

@@ -45,4 +45,13 @@ public interface Saveable {
      *      if the persistence failed.
      */
     void save() throws IOException;
+
+    /**
+     * {@link Saveable} that doesn't save anything.
+     * @since 1.301.
+     */
+    public static final Saveable NOOP = new Saveable() {
+        public void save() throws IOException {
+        }
+    };
 }