ERROR: org.springframework.web.context.ContextLoader - Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in ServletContext resource [/WEB-INF/spring-servlet.xml]: Invocation of init method failed; nested exception is org.hibernate.AnnotationException: Unknown mappedBy in: cz.uhk.ppro.musicbook.entity.User.userRegistration, referenced property unknown: cz.uhk.ppro.musicbook.entity.UserRegistration.user_id
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1512)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:521)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:296)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:293)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:610)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
	at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:389)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:294)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4939)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5434)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:633)
	at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:656)
	at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1635)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
	at java.util.concurrent.FutureTask.run(FutureTask.java:166)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:722)
Caused by: org.hibernate.AnnotationException: Unknown mappedBy in: cz.uhk.ppro.musicbook.entity.User.userRegistration, referenced property unknown: cz.uhk.ppro.musicbook.entity.UserRegistration.user_id
	at org.hibernate.cfg.OneToOneSecondPass.doSecondPass(OneToOneSecondPass.java:160)
	at org.hibernate.cfg.Configuration.originalSecondPassCompile(Configuration.java:1636)
	at org.hibernate.cfg.Configuration.secondPassCompile(Configuration.java:1390)
	at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1781)
	at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1865)
	at org.springframework.orm.hibernate4.LocalSessionFactoryBuilder.buildSessionFactory(LocalSessionFactoryBuilder.java:247)
	at org.springframework.orm.hibernate4.LocalSessionFactoryBean.buildSessionFactory(LocalSessionFactoryBean.java:373)
	at org.springframework.orm.hibernate4.LocalSessionFactoryBean.afterPropertiesSet(LocalSessionFactoryBean.java:358)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1571)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1509)
	... 26 more