Embedded class defined in same file as parent results in NPE when saving parent object

java.lang.NullPointerException
   at org.grails.datastore.gorm.GormInstanceApi.save(GormInstanceApi.groovy:139)
   at org.grails.datastore.gorm.GormEnhancer$1.call(GormEnhancer.groovy:93)
   at demo1.CustomerController$_closure4.doCall(CustomerController.groovy:24)
   at demo1.CustomerController$_closure4.doCall(CustomerController.groovy)
   at java.lang.Thread.run(Thread.java:680)

class Customer {
   String name
   Address address
   static embedded = ['address']
}

class Address {
   String street
}