bson4jackson: Error when trying to deserialize BSON into a EXISTING_PROPERTY polymorphic class

I ran into an problem when trying to deserialize BSON into a polymorphic class that uses JsonTypeInfo.As.EXISTING_PROPERTY.

Groovy script:

@Grab('de.undercouch:bson4jackson:2.7.0')

import com.fasterxml.jackson.annotation.JsonSubTypes
import com.fasterxml.jackson.annotation.JsonTypeInfo
import com.fasterxml.jackson.databind.ObjectMapper
import de.undercouch.bson4jackson.BsonFactory
import de.undercouch.bson4jackson.BsonModule

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXISTING_PROPERTY, property = 'type')
@JsonSubTypes([
    @JsonSubTypes.Type(name = 'a', value = A),
    @JsonSubTypes.Type(name = 'b', value = B)
])
abstract class Base {
    UUID id
    String type
}

class A extends Base {}

class B extends Base {}


def mapper = new ObjectMapper(new BsonFactory()).registerModule(new BsonModule())
def bytes = mapper.writeValueAsBytes(new A(id: UUID.randomUUID()))
mapper.readValue(bytes, Base)

Throws the stacktrace:

Caught: com.fasterxml.jackson.core.JsonGenerationException: BsonSerializer can only be used with BsonGenerator
com.fasterxml.jackson.core.JsonGenerationException: BsonSerializer can only be used with BsonGenerator
        at de.undercouch.bson4jackson.serializers.BsonSerializer.serialize(BsonSerializer.java:37)
        at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:130)
        at com.fasterxml.jackson.databind.ObjectMapper.writeValue(ObjectMapper.java:2436)
        at com.fasterxml.jackson.databind.util.TokenBuffer.writeObject(TokenBuffer.java:849)
        at com.fasterxml.jackson.databind.util.TokenBuffer.copyCurrentEvent(TokenBuffer.java:1006)
        at com.fasterxml.jackson.databind.util.TokenBuffer.copyCurrentStructure(TokenBuffer.java:1048)
        at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer.deserializeTypedFromObject(AsPropertyTypeDeserializer.java:97)
        at com.fasterxml.jackson.databind.deser.AbstractDeserializer.deserializeWithType(AbstractDeserializer.java:142)
        at com.fasterxml.jackson.databind.deser.impl.TypeWrappedDeserializer.deserialize(TypeWrappedDeserializer.java:42)
        at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3788)
        at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2872)
        at com.fasterxml.jackson.databind.ObjectMapper$readValue$1.call(Unknown Source)
        at so.run(so.groovy:27)

Hints:

• When I use JsonTypeInfo.As.PROPERTY the issue goes away.
• When I don’t register BsonModule the issue goes away.
• This was occurring on JDK 7 but not JDK 8. After trying to debug a bit, this appears to be because of reflection field order.