Inline task with anchor link caused AO migration failed

Here are the steps to reproduce the issue:

1. Within version 5.3.4 create a empty page with:
   • an anchor
   • an inline task with the anchor link
2. Upgrade to Confluence 5.5.2.
3. The upgrade is complete but all task found after the task with the anchor link will not be migrated and the following message found in the log:

   2014-06-18 13:55:59,908 ERROR [StorageToAoMigrationUpgradeTask-TaskExtractor-4] [plugins.tasklist.upgradetask.InterruptingUncaughtExceptionHandler] uncaughtException Uncaught exception in thread StorageToAoMigrationUpgradeTask-TaskExtractor-4. Interrupting all threads.
    -- referer: http://mymac:8552/admin/backup.action | url: /admin/restore.action | userName: admin | action: restore
   java.lang.ClassCastException: com.ctc.wstx.evt.WEndElement cannot be cast to javax.xml.stream.events.StartElement
   	at com.ctc.wstx.evt.WEvent.asStartElement(WEvent.java:63)
   	at com.atlassian.confluence.plugins.tasklist.transformer.InlineTaskUserExtractor.extractUsersForInlineTask(InlineTaskUserExtractor.java:57)
   	at com.atlassian.confluence.plugins.tasklist.transformer.InlineTaskFinderImpl.parseTask(InlineTaskFinderImpl.java:164)
   	at com.atlassian.confluence.plugins.tasklist.transformer.InlineTaskFinderImpl.findTasks(InlineTaskFinderImpl.java:130)
   	at com.atlassian.confluence.plugins.tasklist.transformer.InlineTaskFinderImpl.extractTasks(InlineTaskFinderImpl.java:87)
   	at com.atlassian.confluence.plugins.tasklist.upgradetask.StorageToAoMigrationTaskExtractor$1.doInTransaction(StorageToAoMigrationTaskExtractor.java:103)
   	at com.atlassian.confluence.plugins.tasklist.upgradetask.StorageToAoMigrationTaskExtractor$1.doInTransaction(StorageToAoMigrationTaskExtractor.java:86)
   	at com.atlassian.sal.core.transaction.HostContextTransactionTemplate$1.doInTransaction(HostContextTransactionTemplate.java:25)
   	at com.atlassian.sal.spring.component.SpringHostContextAccessor$1.doInTransaction(SpringHostContextAccessor.java:88)
   	at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:128)
   	at com.atlassian.sal.spring.component.SpringHostContextAccessor.doInTransaction(SpringHostContextAccessor.java:82)
   	at sun.reflect.GeneratedMethodAccessor89.invoke(Unknown Source)
   	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
   	at java.lang.reflect.Method.invoke(Method.java:597)
   	at com.atlassian.plugin.osgi.hostcomponents.impl.DefaultComponentRegistrar$ContextClassLoaderSettingInvocationHandler.invoke(DefaultComponentRegistrar.java:129)
   	at com.sun.proxy.$Proxy220.doInTransaction(Unknown Source)
   	at sun.reflect.GeneratedMethodAccessor89.invoke(Unknown Source)
   	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
   	at java.lang.reflect.Method.invoke(Method.java:597)
   	at com.atlassian.plugin.osgi.bridge.external.HostComponentFactoryBean$DynamicServiceInvocationHandler.invoke(HostComponentFactoryBean.java:154)
   	at com.sun.proxy.$Proxy220.doInTransaction(Unknown Source)
   	at com.atlassian.sal.core.transaction.HostContextTransactionTemplate.execute(HostContextTransactionTemplate.java:21)
   	at sun.reflect.GeneratedMethodAccessor106.invoke(Unknown Source)
   	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:307)
   	at org.springframework.osgi.service.importer.support.internal.aop.ServiceInvoker.doInvoke(ServiceInvoker.java:58)
   	at org.springframework.osgi.service.importer.support.internal.aop.ServiceInvoker.invoke(ServiceInvoker.java:62)
   	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
   	at org.springframework.aop.support.DelegatingIntroductionInterceptor.doProceed(DelegatingIntroductionInterceptor.java:131)
   	at org.springframework.aop.support.DelegatingIntroductionInterceptor.invoke(DelegatingIntroductionInterceptor.java:119)
   	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
   	at org.springframework.osgi.service.util.internal.aop.ServiceTCCLInterceptor.invokeUnprivileged(ServiceTCCLInterceptor.java:56)
   	at org.springframework.osgi.service.util.internal.aop.ServiceTCCLInterceptor.invoke(ServiceTCCLInterceptor.java:39)
   	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
   	at org.springframework.osgi.service.importer.support.LocalBundleContextAdvice.invoke(LocalBundleContextAdvice.java:59)
   	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
   	at org.springframework.aop.support.DelegatingIntroductionInterceptor.doProceed(DelegatingIntroductionInterceptor.java:131)
   	at org.springframework.aop.support.DelegatingIntroductionInterceptor.invoke(DelegatingIntroductionInterceptor.java:119)
   	at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
   	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
   	at com.sun.proxy.$Proxy2365.execute(Unknown Source)
   	at com.atlassian.confluence.plugins.tasklist.upgradetask.StorageToAoMigrationTaskExtractor.run(StorageToAoMigrationTaskExtractor.java:85)
   	at java.lang.Thread.run(Thread.java:695)
   2014-06-18 13:55:59,925 ERROR [Long running task: Importing data] [plugins.tasklist.upgradetask.StorageToAoMigrationUpgradeTask] doUpgrade Inline task migration failed! 2 tasks were migrated. You may try rerunning it or contactAtlassian support if it continues to fail.
    -- referer: http://mymac:8552/admin/backup.action | url: /admin/restore.action | userName: admin | action: restore
   2014-06-18 13:55:59,929 WARN [StorageToAoMigrationUpgradeTask-TaskInserter-2] [plugins.tasklist.upgradetask.StorageToAoMigrationTaskInserter] run Task inserter was interrupted. Aborting.
    -- referer: http://mymac:8552/admin/backup.action | url: /admin/restore.action | userName: admin | action: restore
   2014-06-18 13:55:59,930 WARN [StorageToAoMigrationUpgradeTask-TaskInserter-4] [plugins.tasklist.upgradetask.StorageToAoMigrationTaskInserter] run Task inserter was interrupted. Aborting.
    -- referer: http://mymac:8552/admin/backup.action | url: /admin/restore.action | userName: admin | action: restore
   2014-06-18 13:55:59,931 WARN [StorageToAoMigrationUpgradeTask-TaskInserter-3] [plugins.tasklist.upgradetask.StorageToAoMigrationTaskInserter] run Task inserter was interrupted. Aborting.
    -- referer: http://mymac:8552/admin/backup.action | url: /admin/restore.action | userName: admin | action: restore
   2014-06-18 13:55:59,935 WARN [StorageToAoMigrationUpgradeTask-TaskInserter-1] [plugins.tasklist.upgradetask.StorageToAoMigrationTaskInserter] run Task inserter was interrupted. Aborting.
    -- referer: http://mymac:8552/admin/backup.action | url: /admin/restore.action | userName: admin | action: restore
   

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