Dealing with NoClassTag when converting to arrays

[vasigorc]

Hello 👋

I have a very simple case and I couldn't find documentation on how to deal with this 🤷‍♂️

I've declared a new type like this:

@newtype final case class Id(value: String)
@newtype final case class ExternalId(value: String)

Later in the code I finish up with a map mapping: Map[Id, ExternalId]. But when I need to collect it's keys/values to an array I get compilation errors:

val myIds = mapping.keys.toArray
val externalIds = mapping.values.toArray

Error:

No ClassTag available for ...Id
No ClassTag available for ...ExternalId

How is this supposed to be handled. Are newtypes incompatible with arrays because of generics?