CBOR @ByteString should work with value classes

[steffandroid]

What is your use-case and why do you need this feature?

According to the documentation, CBOR's @ByteString annotation can be used in data classes to encode or decode a ByteArray as a byte string (major type 2). This is fine if you're dealing with CBOR data that can be represented as a data class, but there cases where a data class is not suitable (one of which is covered in #2037).

My use-case is to decode a single raw byte string, without any kind of wrapper. Other primitive types can be serialized directly (e.g. Cbor.decodeFromByteArray<Int>(data)) or using a value class:

@JvmInline
@Serializable
value class Value(val data: Int)

which can then be decoded with Cbor.decodeFromByteArray<Value>(data).

This is not possible with byte strings.

Describe the solution you'd like

I would like to be able to define a value class as such:

@JvmInline
@Serializable
value class Value(@ByteString val data: ByteArray)

Currently, if I try using this to decode the byte string 4401020304, I get the following error: kotlinx.serialization.cbor.internal.CborDecodingException: Expected start of array, but found 44.