Package JPA without entities fails with odd error

[philwebb]

Add JPA starter and Web starter but no entities.

Package up and run with java -jar

java.lang.reflect.InvocationTargetException
    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:606)
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:53)
    at java.lang.Thread.run(Thread.java:744)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: Unable to resolve persistence unit root URL
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1553)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:539)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:973)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:750)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:120)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:619)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:306)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:880)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:869)
    at sample.Example.main(Example.java:14)
    ... 6 more
Caused by: javax.persistence.PersistenceException: Unable to resolve persistence unit root URL
    at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.determineDefaultPersistenceUnitRootUrl(DefaultPersistenceUnitManager.java:580)
    at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.preparePersistenceUnitInfos(DefaultPersistenceUnitManager.java:436)
    at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.afterPropertiesSet(DefaultPersistenceUnitManager.java:417)
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:303)
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:318)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1612)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1549)
    ... 21 more
Caused by: java.io.FileNotFoundException: class path resource [] cannot be resolved to URL because it does not exist
    at org.springframework.core.io.ClassPathResource.getURL(ClassPathResource.java:178)
    at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.determineDefaultPersistenceUnitRootUrl(DefaultPersistenceUnitManager.java:577)
    ... 27 more