Provide a default serializer for kotlin.uuid.Uuid class

[sandwwraith]

Kotlin 2.0.20 is expected to have a new MPP UUID class (https://youtrack.jetbrains.com/issue/KT-31880, JetBrains/kotlin@25ea5e8). It is reasonable to provide a built-in serializer for it, like we did for kotlin.time.Duration when it was moved to stdlib.

Adding a built-in serializer requires changes in the plugin too, so they have to be made in time, preferably in the same Kotlin 2.0.20 or Kotlin 2.1

[hfhbd]

How do you want to serialize it for different formats? In string formats, like JSON, properties, xml etc., it is common to use the string representation, but for binary formats, a compact binary (using the two longs directly) would be preferred than encoding the string.

[sandwwraith]

Good question. Initially, I was planning to add only String representation, but maybe binary serializer is also required as an additional one

[sandwwraith]

Apparently, there is no standardized way of storing UUIDs in protobuf (protocolbuffers/protobuf#2224, https://groups.google.com/g/protobuf/c/THxuTQKsz54). Various implementations use string, bytes, or a pair of fixed64/uint64.

For CBOR, there is tag 37 for UUID byte string (https://www.iana.org/assignments/cbor-tags/cbor-tags.xhtml), which is an accepted extension described here: https://github.com/lucas-clemente/cbor-specs/blob/master/uuid.md

So it looks like, for now, only CBOR requires additional handling.

[Chuckame]

On the avro binary format, the uuid is officially represented as a string as said by the spec (the default official uuid type), but is also usually serialized as a fixed of 16 bytes to save space (36 characters/bytes vs 16 bytes), so we may also want to handle a uuid differently depending on the user config.

EDIT:
Btw, this is the same for kotlin.time.Duration where the official representation is a fixed of 12 bytes

[sandwwraith]

Well, in the case of format-specific serializers, you can always mark Duration or Uuid with @Contextual and provide a module for Avro/Cbor. If SerializersModule is empty, a default serializer will be used for e.g. Json.

[bcmedeiros]

Just raised a ticket on the former de-facto uuid implementation for Kotlin with some findings about binary serialization, if anyone is interested: hfhbd/kotlinx-uuid#422