ClassCastException in JpaRepository method that returns Stream<> when running in native image

[andrey-nakin]

I have a JPA repository with the following method:

public interface SampleRepository extends JpaRepository<SampleEntity, Integer> {
    Stream<SampleEntity> findAllByOrderByName();
    ...

The method is used in a REST controller as follows:

    @GetMapping("/samples/first")
    @Transactional(readOnly = true)
    public SampleEntity first() {
        return repository.findAllByOrderByName().findFirst().orElseThrow();

In works well when my application is running as a regular Java app under JRE. But when I build it into a Docker image using Spring Native, the invocation of findFirst() in the code above causes ClassCastException:

java.lang.ClassCastException: com.example.demo.entity.SampleEntity cannot be cast to java.lang.Object[]
	at org.springframework.data.jpa.provider.PersistenceProvider$HibernateScrollableResultsIterator.next(PersistenceProvider.java:394) ~[na:na]
	at [email protected]/java.util.Spliterators$IteratorSpliterator.tryAdvance(Spliterators.java:1856) ~[com.example.demo.DemoApplication:na]

The workaround is to change the repository method's return value from Stream<> to List<>.

Please refer to spring-native-issues repo with a complete demo. Make sure stream-first branch of the repo is used.

[christophstrobl]

This seems to be a duplicate of spring-projects/spring-data-jpa#2848.

[sbrannen]

Indeed, this does look like a duplicate of that issue.

Thanks for the tip, @christophstrobl.

In light of that, I am closing this issue.