Fails when a collection of entities is passed as a Supplier

[arjanvlek]

The library fails with the following setup:

@Entity
public class Person extends AbstractEntity {

    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(
            name = "person_pet",
            joinColumns = @JoinColumn(name = "person_id", referencedColumnName = "id"),
            inverseJoinColumns = @JoinColumn(name = "pet_id", referencedColumnName = "id")
    )
    private List<Pet> pets;

public interface PersonBuildCommand extends AbstractBuildCommand<Person, PersonRepository> {

    @Override
    default Person findEntity(Person input) {
        return getRepository().findByFirstName(input.getFirstName());
    }

    PersonBuildCommand withPets(Supplier<List<Pet>> pets);
}

The following exception is thrown:

java.lang.ClassCastException: java.util.Collections$SingletonList cannot be cast to org.springframework.data.domain.Persistable

	at nl._42.heph.lazy.AbstractLazyEntity.resolve(AbstractLazyEntity.java:43)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at nl._42.heph.DefaultBuildCommand.resolveReferences(DefaultBuildCommand.java:123)
	at nl._42.heph.DefaultBuildCommand.resolveBeforeCreateReferences(DefaultBuildCommand.java:113)
	at nl._42.heph.DefaultBuildCommand.performPreProcessing(DefaultBuildCommand.java:193)
	at nl._42.heph.DefaultBuildCommand.save(DefaultBuildCommand.java:258)
	at nl._42.heph.DefaultBuildCommand.constructOrSave(DefaultBuildCommand.java:277)
	at nl._42.heph.DefaultBuildCommand.create(DefaultBuildCommand.java:299)
	at nl._42.heph.DefaultBuildCommand$$EnhancerByCGLIB$$c0d05c85.CGLIB$create$3(<generated>)
	at nl._42.heph.DefaultBuildCommand$$EnhancerByCGLIB$$c0d05c85$$FastClassByCGLIB$$49ab7324.invoke(<generated>)
	at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244)
	at nl._42.heph.AbstractBuilder.lambda$instantiateBuildCommand$3(AbstractBuilder.java:256)
	at nl._42.heph.DefaultBuildCommand$$EnhancerByCGLIB$$c0d05c85.create(<generated>)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:343)
	at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:206)
	at com.sun.proxy.$Proxy119.create(Unknown Source)
	at nl._42.hephdemo.person.PersonFixtures.robertBor_withBorisTheHamster(PersonFixtures.java:41)
	at nl._42.hephdemo.person.PersonServiceTest.findAll_shouldFindAllPersons_withTheirPets(PersonServiceTest.java:23)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)