DataRefresh extension function throws exception for subclasses of MutableCommonDataEntity

[vestrel00]

Using the DataRefresh extension function on a direct subclass of CommonDataEntity works just fine. For example, to refresh an immutable email,

var email: Email
email = email.refresh(contactsApi)

An exception?!

However, when trying to refresh a mutable email,

var email: MutableEmail
email = email.refresh(contactsApi)

Will throw an exception,

java.lang.ClassCastException: contacts.core.entities.Email cannot be cast to contacts.core.entities.MutableEmail

Why?

The reason this occurs is because of the function signature,

fun <T : CommonDataEntity> T.refresh(...): T? =

Combined with the following class hierarchy,

interface CommonDataEntity
interface MutableCommonDataEntity : CommonDataEntity

data class Email : CommonDataEntity
data class MutableEmail : MutableCommonDataEntity

Allows for the refresh extension function to be callable for MutableEmail given that it is an indirect subclass of CommonDataEntity. However, the refresh function itself only returns immutable instances. So,

var email: MutableEmail?
email = email?.refresh(contactsApi) // returns an instance of `Email`, which cannot be casted to a `MutableEmail`.

[vestrel00]

Technically fixed in https://github.com/vestrel00/contacts-android/pull/114/files#r757986465 but there is a remaining TODO

[vestrel00]

This is a part of v0.1.9 Release Checklist.