SnipSnap Import does not work in Confluence 3.5

Steps to Reproduce

1. Download snipsnap sample data from CSP-54610 (restricted to public)
2. Import it in Confluence 3.5.
3. The process will run and fail with something like this: "Import failed. null"
   
4. There will be a lot of these kind of warning messages in the log:

   2011-03-29 21:48:41,902 WARN [Importing data task] [importexport.impl.snipsnap.SnipSnapImporter] mungeTitle Renamed snip [Development/Framework Evaluation] to Confluence page [Development-Framework Evaluation]
    -- referer: http://localhost:8035/admin/snipsnapimport-start.action | url: /admin/snipsnapimport.action | userName: admin | action: snipsnapimport
   

5. And it will end up with NPE:

   2011-03-29 21:48:47,890 ERROR [Importing data task] [confluence.importexport.actions.ImportLongRunningTask] runInternal Failure during import
    -- referer: http://localhost:8035/admin/snipsnapimport-start.action | url: /admin/snipsnapimport.action | userName: admin | action: snipsnapimport
   java.lang.NullPointerException
   	at com.atlassian.confluence.importexport.Importer.publishEvent(Importer.java:129)
   	at com.atlassian.confluence.importexport.Importer.doImport(Importer.java:78)
   	at com.atlassian.confluence.importexport.DefaultImportExportManager.importAs(DefaultImportExportManager.java:74)
   	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.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:304)
   	at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
   	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
   	at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
   	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
   	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
   	at $Proxy81.importAs(Unknown Source)
   	at com.atlassian.confluence.importexport.actions.ImportLongRunningTask.runInternal(ImportLongRunningTask.java:55)
   	at com.atlassian.confluence.util.longrunning.ConfluenceAbstractLongRunningTask.run(ConfluenceAbstractLongRunningTask.java:21)
   	at java.lang.Thread.run(Thread.java:662)
   

Finding

The same snipsnap data can be imported successfully in Confluence 3.4.9

Workaround

Import the snipsnap data in Confluence 3.4.x, then proceed either one of the following:

• Upgrade the instance to Confluence 3.5.x
• Export the Space to XML and import it in Confluence 3.5.x. You will need to modify the buildnumber of the Space XML backup as described here.