Mongo Java Driver ~ @BsonDiscriminator mapping parent instead of child class

I am trying to write and read a complex object to a MongoDB using Java Mongo Driver.

The object includes among other things Lists of Objects of different but related type that I cover with abstract classes in the data model, for example:

public class Datatypes{
    public List<DatatypeDefinitionTag> datatypeDefinitions;
}

…which gets filled with these objects:

public class DatatypeDefinitionInteger extends DatatypeDefinitionTag {
    [...]
}

public class DatatypeDefinitionString extends DatatypeDefinitionTag {
    [...]
}

Now, according to the documentation (http://mongodb.github.io/mongo-java-driver/3.9/bson/pojos/#properties-with-abstract-or-interface-types) this should work by annotating the abstract class as follows:

@BsonDiscriminator
public abstract class DatatypeDefinitionTag {
    [...]
}

…however, if I do that, I still get an error while trying to read data from the MongoDB, and checking the MongoDB directly, I can see that all entries under datatypeDefinitions have _t:reqIF.reqIF_dataStructure.abstracts.tags.DatatypeDefinitionTag

I would have expected the discriminator to assign the following values instead, based on the saved object:

  • _t:reqIF.reqIF_dataStructure.coreContent.reqIF_content.datatypes.datatypeDefinitions.DatatypeDefinitionString
  • _t:reqIF.reqIF_dataStructure.coreContent.reqIF_content.datatypes.datatypeDefinitions.DatatypeDefinitionInteger

Any idea why this is happening? In essence, I am just looking for the Java equivalent of how this would work with the .Net Driver:

[BsonKnownTypes(typeof(DatatypeDefinitionString), typeof(DatatypeDefinitionInteger))]
public class DatatypeDefinitionTag 

I have now created a minimalistic test project that replicates this exact behavior (run the MongoDB_ReaderTest to replicate):

I figured out what caused this.
I was using a too-old version of the MongoDB driver.
Now I use org.mongodb:mongodb-driver:3.6.0 , and it works perfectly.