Null in shipping cost results in Exception during order creation phase in checkout.

Need to ensure that the shipping cost column is not null in carrier SLA.
Also need to ensure that shipping cost calculation do not produce null but rather zero.
This issue occurred when SLA are imported via CSV and no price is specified. Through YUM there is no issue as zeros are put in DTO forcefully.

15:25:24,030 WARN StatefulPersistenceContext:722 - HHH000179: Narrowing proxy to class org.yes.cart.domain.entity.impl.ShopEntity - this operation breaks ==
15:25:24,038 WARN StatefulPersistenceContext:722 - HHH000179: Narrowing proxy to class org.yes.cart.domain.entity.impl.WarehouseEntity - this operation breaks ==
15:25:24,125 ERROR DefaultExceptionMapper:114 - Unexpected error occurred
org.apache.wicket.WicketRuntimeException: Can't instantiate page using constructor 'public ua.lana.web.page.lana1.CheckoutPage(org.apache.wicket.request.mapper.parameter.PageParameters)' and argument 'thp=[true], step=[payment]'. Might be it doesn't exist, may be it is not visible (public).
at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:193)
at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:98)
at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:46)
at org.apache.wicket.DefaultMapperContext.newPageInstance(DefaultMapperContext.java:107)
at org.apache.wicket.request.handler.PageProvider.resolvePageInstance(PageProvider.java:274)
at org.apache.wicket.request.handler.PageProvider.getPageInstance(PageProvider.java:165)
at org.apache.wicket.request.handler.render.PageRenderer.getPage(PageRenderer.java:78)
at org.apache.wicket.request.handler.render.WebPageRenderer.renderPage(WebPageRenderer.java:93)
at org.apache.wicket.request.handler.render.WebPageRenderer.respond(WebPageRenderer.java:237)
at org.apache.wicket.request.handler.RenderPageRequestHandler.respond(RenderPageRequestHandler.java:167)
at org.apache.wicket.request.cycle.RequestCycle$HandlerExecutor.respond(RequestCycle.java:784)
at org.apache.wicket.request.RequestHandlerStack.execute(RequestHandlerStack.java:64)
at org.apache.wicket.request.cycle.RequestCycle.execute(RequestCycle.java:255)
at org.apache.wicket.request.cycle.RequestCycle.processRequest(RequestCycle.java:212)
at org.apache.wicket.request.cycle.RequestCycle.processRequestAndDetach(RequestCycle.java:283)
at org.apache.wicket.protocol.http.WicketFilter.processRequest(WicketFilter.java:188)
at org.apache.wicket.protocol.http.WicketFilter.doFilter(WicketFilter.java:244)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.yes.cart.web.filter.AbstractFilter.doFilter(AbstractFilter.java:62)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.yes.cart.web.filter.AbstractFilter.doFilter(AbstractFilter.java:62)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:259)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:987)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1146)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:679)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedConstructorAccessor253.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
at org.apache.wicket.session.DefaultPageFactory.newPage(DefaultPageFactory.java:170)
... 46 more
Caused by: org.hibernate.PropertyValueException: not-null property references a null or transient value: org.yes.cart.domain.entity.impl.CustomerOrderDeliveryEntity.price
at org.hibernate.engine.internal.Nullability.checkNullability(Nullability.java:103)
at org.hibernate.action.internal.AbstractEntityInsertAction.nullifyTransientReferencesIfNotAlready(AbstractEntityInsertAction.java:132)
at org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:69)
at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:362)
at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:203)
at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:183)
at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:167)
at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:321)
at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:286)
at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:192)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:204)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:189)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:114)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
at org.hibernate.internal.SessionImpl.fireSaveOrUpdate(SessionImpl.java:734)
at org.hibernate.internal.SessionImpl.saveOrUpdate(SessionImpl.java:726)
at org.hibernate.engine.spi.CascadingAction$5.cascade(CascadingAction.java:258)
at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:387)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:330)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
at org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:416)
at org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:357)
at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:333)
at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:208)
at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:165)
at org.hibernate.event.internal.AbstractSaveEventListener.cascadeAfterSave(AbstractSaveEventListener.java:449)
at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:292)
at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:192)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:204)
at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:55)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:189)
at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:49)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:763)
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:755)
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:751)
at org.yes.cart.dao.impl.GenericDAOHibernateImpl.create(GenericDAOHibernateImpl.java:351)
at org.yes.cart.service.domain.impl.BaseGenericServiceImpl.create(BaseGenericServiceImpl.java:58)
at org.yes.cart.service.domain.impl.CustomerOrderServiceImpl.createFromCart(CustomerOrderServiceImpl.java:178)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:319)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
at sun.proxy.$Proxy227.createFromCart(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.apache.wicket.proxy.LazyInitProxyFactory$JdkHandler.invoke(LazyInitProxyFactory.java:431)
at org.apache.wicket.proxy.$Proxy349.createFromCart(Unknown Source)
at ua.lana.web.page.lana1.CheckoutPage.<init>(CheckoutPage.java:186)
... 50 more