Well it seems null is not supported at all: ```@Se...

# serialization

[Paul Woitaschek]

Well it seems null is not supported at all:

@Serializable
data class Test(
    @ProtoId(1)
    val type: String?,
    @ProtoId(2)
    val userId: String
)

fun main() {
    ProtoBuf.dump(Test.serializer(), Test(null, "b"))
}

This immediately throws an exception:

at kotlinx.serialization.internal.TaggedEncoder.encodeTaggedNull(Tagged.kt:37)
	at kotlinx.serialization.internal.TaggedEncoder.encodeNull(Tagged.kt:71)
	at kotlinx.serialization.Encoder$DefaultImpls.encodeNullableSerializableValue(Encoding.kt:260)
	at kotlinx.serialization.internal.TaggedEncoder.encodeNullableSerializableValue(Tagged.kt:22)
	at kotlinx.serialization.internal.TaggedEncoder.encodeNullableSerializableElement(Tagged.kt:124)
	at Test.write$Self(MessagePoly.kt)