在Hibernate 5.2中获取sessionFactory的这种变体有什么问题？

@Bean
public SessionFactory sessionFactory() throws IOException {
    LocalSessionFactoryBean localSessionFactoryBean = new LocalSessionFactoryBean();
    localSessionFactoryBean.setDataSource(dataSource());
    localSessionFactoryBean.setPackagesToScan(new String[] { "com.test.core.domain.*" });
    localSessionFactoryBean.setMappingLocations(loadResources());
    localSessionFactoryBean.setHibernateProperties(hibernateProperties());
    localSessionFactoryBean.afterPropertiesSet();

    return localSessionFactoryBean.getObject();
}

它引发NullPointerException：

引起：org.springframework.beans.BeanInstantiationException：无法实例化[org.hibernate.SessionFactory]：工厂方法'sessionFactory'抛出异常;嵌套异常是org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate（SimpleInstantiationStrategy.java:185）中的java.lang.NullPointerException，位于org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod（ConstructorResolver.java:579）在显示java.lang.NullPointerException org.hibernate.metamodel.internal.AttributeFactory.getMetaModelType（AttributeFactory.java:202）在org.hibernate.metamodel.internal.AttributeFactory.buildPluralAttribute（AttributeFactory.java:176：... 75多所致）在org.hibernate.metamodel.internal.AttributeFactory.buildAttribute（AttributeFactory.java:82）在org.hibernate.metamodel.internal.MetadataContext.wrapUp（MetadataContext.java:213）在org.hibernate.metamodel.internal.MetamodelImpl . 在org.hibe的org.hibernate.boot.internal.SessionFactoryBuilderImpl.build（SessionFactoryBuilderImpl.java:460）的org.hibernate.internal.SessionFactoryImpl . （SessionFactoryImpl.java:300）初始化（MetamodelImpl.java:220） rnate.cfg.Configuration.buildSessionFactory（Configuration.java:710）在org.hibernate.cfg.Configuration.buildSessionFactory（Configuration.java:726）在org.springframework.orm.hibernate5.LocalSessionFactoryBean.buildSessionFactory（LocalSessionFactoryBean.java:535）在org.springframework.orm.hibernate5.LocalSessionFactoryBean.afterPropertiesSet（LocalSessionFactoryBean.java:519）在com.ya0ne.core.config.HibernateConfiguration.sessionFactory（HibernateConfiguration.java:46）在com.ya0ne.core.config.HibernateConfiguration $$在com.ya0ne.core.config.HibernateConfiguration $$ EnhancerBySpringCGLIB $$ 8f9edb09 $$ FastClassBySpringCGLIB $$ 4b721c9d.invoke（）at org.springframework.cglib.proxy.MethodProxy.invokeSuper（EnhancerBySpringCGLIB $$ 8f9edb09.CGLIB $ sessionFactory $ 2（） MethodProxy.java:228）在org.springframework.context.annotation.ConfigurationClassEnhancer $ BeanMethodInterceptor.intercept（ConfigurationClassEnhancer.java:361）在com.ya0ne.core.config.HibernateConfiguration $$ EnhancerBySpringCGLIB $$ 8f9edb 09.sessionFactory（）在sun.reflect.NativeMethodAccessorImpl.invoke0（本机方法）在sun.reflect.NativeMethodAccessorImpl.invoke（NativeMethodAccessorImpl.java:62）在sun.reflect.DelegatingMethodAccessorImpl.invoke（DelegatingMethodAccessorImpl.java:43）在java的 . lang.reflect.Method.invoke（Method.java:498）org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate（SimpleInstantiationStrategy.java:154）... 76更多

什么是元数据以及我需要添加它的原因？

java hibernate