Summary

I'm trying to deserialize the following Kotlin class:

{{{}data class BsonDocumentUser(
    val a: String = "Bob",
    val b: Int,
{}}})

with the document

{{

}}

which fails with

Caused by: org.bson.codecs.configuration.CodecConfigurationException: Unable to invoke primary constructor of BsonDocumentUser data class
at org.bson.codecs.kotlin.DataClassCodec.decode(DataClassCodec.kt:106)
... 301 more
Caused by: java.lang.reflect.InvocationTargetException
at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:483)
at kotlin.reflect.jvm.internal.calls.CallerImpl$Constructor.call(CallerImpl.kt:41)
at kotlin.reflect.jvm.internal.DescriptorKCallable.callDefaultMethod(DescriptorKCallable.kt:240)
at kotlin.reflect.jvm.internal.DescriptorKCallable.callBy(DescriptorKCallable.kt:145)
at org.bson.codecs.kotlin.DataClassCodec.decode(DataClassCodec.kt:104)
... 302 more
Caused by: java.lang.NullPointerException: Parameter specified as non-null is null: method opensavvy.ktmongo.bson.BsonDocumentUser.<init>, parameter a
at opensavvy.ktmongo.bson.BsonDocumentUser.<init>(BsonDocumentTests.kt)
... 308 more

Please provide the version of the driver. If applicable, please provide the MongoDB server version and topology (standalone, replica set, or sharded cluster).

5.6.2

Additional Background

The problem seems to be in

org.bson.codecs.kotlin.DataClassCodec#decode

The call is:

primaryConstructor.callBy(args)

where args contains all parameters, with a null value if the parameter is not found in the document.

If the argument was not present at all in the map, kotlin-reflect would substitute it by the default value.