Adding my own properties to a person object

[#1]

I'm trying to follow the blog post (http://ecmarchitect.com/archives/2012/02/27/1555) of Jeff Potts about adding new properties to a person object. One step is extending the org.alfresco.web.site.SlingshotUserFactory. I have done so beside the other steps in this tutorial. When I deploy my jars (share and repo) to an alfresco enterprise installation (4.0.2) I get following error saving the profil of the user (not the full stack trace is shown here):

2012-10-01 22:55:31,719  ERROR [extensions.webscripts.AbstractRuntime] [http-8080-4] Exception from executeScript - redirecting to status template error: 09010001 Failed to execute script 'classpath*:alfresco/site-webscripts/org/alfresco/components/profile/userprofile.post.json.js': 09010000 org.springframework.extensions.webscripts.json.JSONWriter.startObject()V
 org.springframework.extensions.webscripts.WebScriptException: 09010001 Failed to execute script 'classpath*:alfresco/site-webscripts/org/alfresco/components/profile/userprofile.post.json.js': 09010000 org.springframework.extensions.webscripts.json.JSONWriter.startObject()V
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Later on in the shown stack trace my extended SlingshotUserFactory class de.ppi.share.PpiUserFactory is mentioned.

Caused by: java.lang.NoSuchMethodError: org.springframework.extensions.webscripts.json.JSONWriter.startObject()V
   at de.ppi.share.PpiUserFactory.saveUser(PpiUserFactory.java:75)
   at org.alfresco.web.site.SlingshotUser.save(SlingshotUser.java:55)
   at org.springframework.extensions.webscripts.ScriptUser.save(ScriptUser.java:317)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
   at java.lang.reflect.Method.invoke(Method.java:597)
   at org.mozilla.javascript.MemberBox.invoke(MemberBox.java:155)
   at org.mozilla.javascript.NativeJavaMethod.call(NativeJavaMethod.java:243)
   at org.mozilla.javascript.optimizer.OptRuntime.callProp0(OptRuntime.java:119)
   at org.mozilla.javascript.gen.c16._c1(file:/C:/PPI/Alfresco_EE/tomcat/webapps/share/WEB-INF/classes/alfresco/site-webscripts/org/alfresco/components/profile/userprofile.post.json.js:43)
   at org.mozilla.javascript.gen.c16.call(file:/C:/PPI/Alfresco_EE/tomcat/webapps/share/WEB-INF/classes/alfresco/site-webscripts/org/alfresco/components/profile/userprofile.post.json.js)
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Below a code snipet of the part where the error occurs.

….
public class PpiUserFactory extends SlingshotUserFactory {      
….
StringBuilderWriter buf = new StringBuilderWriter(512);
JSONWriter writer = new JSONWriter(buf);
         
try {
   writer.startObject();
   …
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An object of the JSONWriter class is created and the method startObject() is called. I have no compile error but obviously in the runtime. I check the spring-webscripts-1.0.0.jar for the missing method but it is there. I have no idea why this error occur. Could anybody help me with this problem?

[#2]

I solved the problem. In the pom I used a wrong version of the dependent libraries with the groupId org.springframework.extensions.surf. Instead 1.0.0 which is the right version the mentioned problems does not occur I declared the version 1.0.0.M3.