Problem deserializing EmbeddedId after reastart

[tkuprevich]

We have an entity having @OneToMany relation to another entity having composite key mapped as @EmbeddedId.

@TypeName("Agreement")
class Agreement {
        @Id
        private UUID agreementId;

        private UUID locationId;

        @OneToMany(mappedBy = "agreement", cascade = CascadeType.ALL, orphanRemoval = true)
        @ShallowReference
        private List<AgreementMember> agreementMembers;

        //other fields ...
 }

Many side:

@TypeName("AgreementMember")
class AgreementMember {

     public AgreementMemberId getId() {
         return agreementMemberId;
     }

     @Embeddable
     @TypeName("AgreementMemberId")
     public static class AgreementMemberId implements Serializable {
         private UUID agreementId;
         private UUID memberId;

         UUID getAgreementId() {
             return agreementId
         }

         void setAgreementId(UUID agreementId) {
             this.agreementId = agreementId
         }

         UUID getMemberId() {
             return memberId
         }

         void setMemberId(UUID memberId) {
             this.memberId = memberId
         }
     }

     @EmbeddedId
     private AgreementMemberId agreementMemberId;

     //other fields ...
}

And also we have registered TypeAdapter for EmbeddedId:

class AgreementMemberIdTypeAdapter extends TypeAdapter<AgreementMember.AgreementMemberId> {

        @Override
        public void write(JsonWriter jsonWriter, AgreementMember.AgreementMemberId agreementMemberId) throws IOException {
            if (agreementMemberId != null)//todo
            {
                jsonWriter.beginObject();
                if (agreementMemberId.getAgreementId() != null) {
                    jsonWriter.name("agreementId").value(agreementMemberId.getAgreementId().toString());
                }
                if (agreementMemberId.getMemberId() != null) {
                    jsonWriter.name("memberId").value(agreementMemberId.getMemberId().toString());
                }
                jsonWriter.endObject();
            }
        }

        @Override
        public AgreementMember.AgreementMemberId read(JsonReader jsonReader) throws IOException {
            AgreementMember.AgreementMemberId agreementMemberId = new AgreementMember.AgreementMemberId();

            jsonReader.beginObject();
            while (jsonReader.hasNext()) {
                switch (jsonReader.nextName()) {
                    case "agreementId":
                        agreementMemberId.setAgreementId(UUID.fromString(jsonReader.nextString()));
                        break;
                    case "memberId":
                        agreementMemberId.setMemberId(UUID.fromString(jsonReader.nextString()));
                        break;
                    default:
                        break;
                }
            }
            jsonReader.endObject();

            return agreementMemberId;
        }
    }

We read snapshots using id and typeName for parent entity;

JqlQuery query = QueryBuilder.byInstanceId(agreement.agreementId, "Agreement").build()

And everything is read correctly until we restart the server. After that the collection of embedded ids comes row (doesn't get deserialized). And managedType references java.lang.Object as baseJavaClass instead of expected Agreement user class in downloaded snapshots.

If we create a query like QueryBuilder.byInstanceId(agreement.agreementId, Agreement.class) everything works correctly before and after restart.

Please see the test case demonstrating the problem: #896
And related stackoverflow discussion: https://stackoverflow.com/questions/58269576/javers-is-it-possible-to-get-cdosnapshotserialized-instance

[bartoszwalacik]

@tkuprevich there is a lot of noise in your test. I did the cleanup here:
https://github.com/javers/javers/pull/909/files

In the first read, in snapshots1.get(0).state.getPropertyValue("agreementMembers")[0] you get InstanceId, which is right because you are using ShallowReference here.

In the second read, in snapshots2.get(0).state.getPropertyValue("agreementMembers")[0] you get badly deserialized InstanceId, I admit. Can you confirm that this is your case?

[bartoszwalacik]

This is a documentation issue and not a bug in javers :)

In 5.8.4 I have added the warning when @TypeName is used on a class without declaring its package name in packagesToScan. Docs for @TypeName and JaversBuilder.withPackagesToScan() are updated.

07:12:58.253 [main] WARN  o.j.core.metamodel.type.UnknownType - Missing class definition with @TypeName 'Agreement', 
cant't properly deserialize its Snapshots from JaversRepository.
To fix this issue provide the fully-qualified package name of the class named 'Agreement' in the packagesToScan property.

[tomekstankowski]

It's worth to mention that classes annotated with @TypeName must be public.

[bartoszwalacik]

@tomekstankowski feel free to contribute a PR that would add this info