I'm not sure why yet but I am seeing the same exception inside of org.hibernate.property.access.spi.GetterFieldImpl.get(Object owner). Inside of this method, I see:

this.containerClass.name = org.jboss.as.test.integration.hibernate.search.Book
this.containerClass.classLoader = org.jboss.as.jpa.classloader.TempClassLoader
owner.getClass().getClassLoader() = application deployment classloader