Error inserting NULL values in NOT-NULL fields under Oracle for Version Comments/Authors

After pressing "Save & Continue" button exception is thrown

Error number 3201 in 3: Exception while saving document XWiki.XWikiPreferences
Wrapped Exception: could not insert: [com.xpn.xwiki.doc.rcs.XWikiRCSNodeInfo]
com.xpn.xwiki.XWikiException: Error number 3201 in 3: Exception while saving document XWiki.XWikiPreferences
Wrapped Exception: could not insert: [com.xpn.xwiki.doc.rcs.XWikiRCSNodeInfo]
at com.xpn.xwiki.store.XWikiHibernateStore.saveXWikiDoc(XWikiHibernateStore.java:333)
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:1018)
at com.xpn.xwiki.web.SaveAction.save(SaveAction.java:120)
at com.xpn.xwiki.web.SaveAndContinueAction.action(SaveAndContinueAction.java:64)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:147)
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:763)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.evermind.server.http.ResourceFilterChain.doFilter(ResourceFilterChain.java:64)
at com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:117)
at com.evermind.server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:622)
at com.evermind.server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:369)
at com.evermind.server.http.HttpRequestHandler.doProcessRequest(HttpRequestHandler.java:865)
at com.evermind.server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:447)
at com.evermind.server.http.HttpRequestHandler.serveOneRequest(HttpRequestHandler.java:215)
at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:117)
at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:110)
at oracle.oc4j.network.ServerSocketReadHandler$SafeRunnable.run(ServerSocketReadHandler.java:260)
at oracle.oc4j.network.ServerSocketAcceptHandler.procClientSocket(ServerSocketAcceptHandler.java:239)
at oracle.oc4j.network.ServerSocketAcceptHandler.access$700(ServerSocketAcceptHandler.java:34)
at oracle.oc4j.network.ServerSocketAcceptHandler$AcceptHandlerHorse.run(ServerSocketAcceptHandler.java:880)
at com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:303)
at java.lang.Thread.run(Thread.java:595)

Wrapped Exception:

java.sql.SQLException: ORA-01400: cannot insert NULL into ("XWIKI"."XWIKIRCS"."XWR_COMMENT")

at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:138)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:316)
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:282)
at oracle.jdbc.driver.T4C8Oall.receive(T4C8Oall.java:639)
at oracle.jdbc.driver.T4CPreparedStatement.doOall8(T4CPreparedStatement.java:185)
at oracle.jdbc.driver.T4CPreparedStatement.execute_for_rows(T4CPreparedStatement.java:633)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1161)
at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3001)
at oracle.jdbc.driver.OraclePreparedStatement.executeUpdate(OraclePreparedStatement.java:3074)
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:2062)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2427)
at org.hibernate.action.EntityInsertAction.execute(EntityInsertAction.java:51)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:248)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:232)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:139)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:297)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:985)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:333)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
at com.xpn.xwiki.store.XWikiHibernateBaseStore.endTransaction(XWikiHibernateBaseStore.java:701)
at com.xpn.xwiki.store.XWikiHibernateBaseStore.endTransaction(XWikiHibernateBaseStore.java:675)
at com.xpn.xwiki.store.XWikiHibernateStore.saveXWikiDoc(XWikiHibernateStore.java:323)
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:1018)
at com.xpn.xwiki.web.SaveAction.save(SaveAction.java:120)
at com.xpn.xwiki.web.SaveAndContinueAction.action(SaveAndContinueAction.java:64)
at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:147)
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:763)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.evermind.server.http.ResourceFilterChain.doFilter(ResourceFilterChain.java:64)
at com.xpn.xwiki.web.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:117)
at com.evermind.server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:622)
at com.evermind.server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:369)
at com.evermind.server.http.HttpRequestHandler.doProcessRequest(HttpRequestHandler.java:865)
at com.evermind.server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:447)
at com.evermind.server.http.HttpRequestHandler.serveOneRequest(HttpRequestHandler.java:215)
at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:117)
at com.evermind.server.http.HttpRequestHandler.run(HttpRequestHandler.java:110)
at oracle.oc4j.network.ServerSocketReadHandler$SafeRunnable.run(ServerSocketReadHandler.java:260)
at oracle.oc4j.network.ServerSocketAcceptHandler.procClientSocket(ServerSocketAcceptHandler.java:239)
at oracle.oc4j.network.ServerSocketAcceptHandler.access$700(ServerSocketAcceptHandler.java:34)
at oracle.oc4j.network.ServerSocketAcceptHandler$AcceptHandlerHorse.run(ServerSocketAcceptHandler.java:880)
at com.evermind.util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:303)
at java.lang.Thread.run(Thread.java:595)