Error while importing xwiki-enterprise-manager-application-xem-1.2.xar : XemManager.Install importing error (oracle 10.2 database)

After installing Manager application on XE 1.4.1 (java 6u3, tomcat 6.0.14, Oracle 10.2.0.3.0), import of xwiki-enterprise-manager-application-xem-1.2.xar failed on the XemManager.Install file with error in logs :

2008-06-11 16:30:10,125 https://164.2.245.3/xwiki/bin/import/XWiki/Import?editor=import&space=XWiki [TP-Processor8] WARN util.JDBCExceptionReporter - SQL Error: 1400, SQLState: 23000
2008-06-11 16:30:10,125 https://164.2.245.3/xwiki/bin/import/XWiki/Import?editor=import&space=XWiki [TP-Processor8] ERROR util.JDBCExceptionReporter - ORA-01400: impossible d'insérer NULL dans ("XWIKI"."XWIKIOBJECTS"."XWO_CLASSNAME")

2008-06-11 16:30:10,125 https://164.2.245.3/xwiki/bin/import/XWiki/Import?editor=import&space=XWiki [TP-Processor8] ERROR .AbstractFlushingEventListener - Could not synchronize database state with session
org.hibernate.exception.ConstraintViolationException: could not insert: [com.xpn.xwiki.objects.BaseObject]
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:71)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2267)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2660)
at org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:56)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:250)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:234)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:141)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:298)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:338)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
at com.xpn.xwiki.store.XWikiHibernateBaseStore.endTransaction(XWikiHibernateBaseStore.java:816)
at com.xpn.xwiki.store.XWikiHibernateBaseStore.endTransaction(XWikiHibernateBaseStore.java:787)
at com.xpn.xwiki.store.XWikiHibernateStore.saveXWikiDoc(XWikiHibernateStore.java:563)
at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:97)
at com.xpn.xwiki.store.XWikiCacheStore.saveXWikiDoc(XWikiCacheStore.java:91)
at com.xpn.xwiki.XWiki.saveDocument(XWiki.java:1131)
at com.xpn.xwiki.XWiki.saveDocument(XWiki.java:1099)
at com.xpn.xwiki.XWiki.saveDocument(XWiki.java:1093)
at com.xpn.xwiki.plugin.packaging.Package.installDocument(Package.java:612)
at com.xpn.xwiki.plugin.packaging.Package.install(Package.java:545)
at com.xpn.xwiki.plugin.packaging.PackageAPI.install(PackageAPI.java:228)
at com.xpn.xwiki.web.ImportAction.render(ImportAction.java:89)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:215)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:112)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:263)
at org.apache.jk.server.JkCoyoteHandler.invoke(JkCoyoteHandler.java:190)
at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:283)
at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:767)
at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:697)
at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(ChannelSocket.java:889)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:690)
at java.lang.Thread.run(Unknown Source)
Caused by: java.sql.SQLException: ORA-01400: impossible d'insérer NULL dans ("XWIKI"."XWIKIOBJECTS"."XWO_CLASSNAME")

at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:331)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:288)
at oracle.jdbc.driver.T4C8Oall.receive(T4C8Oall.java:743)
at oracle.jdbc.driver.T4CPreparedStatement.doOall8(T4CPreparedStatement.java:216)
at oracle.jdbc.driver.T4CPreparedStatement.executeForRows(T4CPreparedStatement.java:955)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1168)
at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3316)
at oracle.jdbc.driver.OraclePreparedStatement.executeUpdate(OraclePreparedStatement.java:3400)
at org.apache.commons.dbcp.DelegatingPreparedStatement.executeUpdate(DelegatingPreparedStatement.java:101)
at org.apache.commons.dbcp.DelegatingPreparedStatement.executeUpdate(DelegatingPreparedStatement.java:101)
at org.hibernate.jdbc.NonBatchingBatcher.addToBatch(NonBatchingBatcher.java:23)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2247)
... 47 more
2008-06-11 16:30:10,140 https://164.2.245.3/xwiki/bin/import/XWiki/Import?editor=import&space=XWiki [TP-Processor8] ERROR packaging.Package - Failed to save document XemManager.Install
[ERROR] Left side ($request.withversions) of '==' operation has null value. If a reference, it may not be in the context. Operation not possible. /templates/importinline.vm [line 16, column 73]