Made no arg constructor protected to enable unit test coverage.

adapters/jetty/src/main/java/org/acegisecurity/adapters/jetty/JettyAcegiUserToken.java

@@ -43,7 +43,7 @@ public class JettyAcegiUserToken extends AbstractAdapterAuthenticationToken
         this.password = password;
     }
 
-    private JettyAcegiUserToken() {
+    protected JettyAcegiUserToken() {
         super();
     }