SEVERE: AJP-0001 Category=7 Message=com.openexchange.usm.eas.delegate.sync.ContactsEmptyObjectFilter.getOriginalSyncID()J exceptionID=1124118876-27
AJP-0001 Category=7 Message=com.openexchange.usm.eas.delegate.sync.ContactsEmptyObjectFilter.getOriginalSyncID()J exceptionID=1124118876-27
        at com.openexchange.ajp13.najp.AJPv13Task.call(AJPv13Task.java:399)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:269)
        at java.util.concurrent.FutureTask.run(FutureTask.java:123)
        at com.openexchange.threadpool.internal.CustomThreadPoolExecutor$Worker.runTask(CustomThreadPoolExecutor.java:750)
        at com.openexchange.threadpool.internal.CustomThreadPoolExecutor$Worker.run(CustomThreadPoolExecutor.java:776)
        at java.lang.Thread.run(Thread.java:595)
Caused by: java.lang.AbstractMethodError: com.openexchange.usm.eas.delegate.sync.ContactsEmptyObjectFilter.getOriginalSyncID()J
        at com.openexchange.usm.session.sync.FolderElementsStorage.<init>(FolderElementsStorage.java:76)
        at com.openexchange.usm.session.impl.SessionImpl.createFolderElementsStorage(SessionImpl.java:319)
        at com.openexchange.usm.session.impl.SessionImpl.syncWithServer(SessionImpl.java:306)
        at com.openexchange.usm.eas.delegate.GetItemEstimateDelegate.computeChanges(GetItemEstimateDelegate.java:152)
        at com.openexchange.usm.eas.delegate.GetItemEstimateDelegate.handleRequest(GetItemEstimateDelegate.java:106)
        at com.openexchange.usm.eas.delegate.BaseXMLDelegate.handleRequest(BaseXMLDelegate.java:96)
        at com.openexchange.usm.eas.servlet.EASServlet.handleRequest(EASServlet.java:483)
        at com.openexchange.usm.eas.servlet.EASServlet.doPost(EASServlet.java:370)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:616)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
        at com.openexchange.ajp13.najp.AJPv13RequestHandlerImpl.doServletService(AJPv13RequestHandlerImpl.java:523)
        at com.openexchange.ajp13.AJPv13Request.response(AJPv13Request.java:134)
        at com.openexchange.ajp13.najp.AJPv13RequestHandlerImpl.createResponse(AJPv13RequestHandlerImpl.java:335)
        at com.openexchange.ajp13.najp.AJPv13ConnectionImpl.createResponse(AJPv13ConnectionImpl.java:227)
        at com.openexchange.ajp13.najp.AJPv13Task.call(AJPv13Task.java:352)
        ... 5 more