Kotlinx Serialization with Variable Fields

SerializationVariableFields.kt

// What is the best way to handle deserialization of JSON
// when one of the fields can be encoded with any of 
// several different names (e.g. 'judgeContent and
// 'mentorContent', which all deserialize to the 
// `Contribution.content` property of `User.user_contributions`)?

@Serializable data class UserData(val name: String)

@Serializable
data class User(
    val user_data: UserData, 
    val user_contributions: List<Contribution>
) {}

interface Action {
    val id: String
}

@Polymorphic interface Content

@Polymorphic interface Contribution : Action {
    val content: Content
}

@Serializable data class Mentor(
    override val id: String,
    
    @SerialName("mentorContent")
    override val content: MentorContent
) : Contribution {
    @Serializable data class MentorContent(val mentor: String, val mentee: String) : Content
}

@Serializable data class Judge(
    override val id: String,
    
    @SerialName("judgeContent")
    override val content: JudgeContent
) : Contribution {
    @Serializable data class JudgeContent(val judge: String, val judged: String) : Content
}

// Given this JSON:

{
    "user_data": {
        "name": "Justin"
    },
    "user_contributions": [
        {
            "id": "1",
            "mentorContent": {
                "mentor": "Lisa",
                "mentee": "Phil"
            }
        },
        {
            "id": "2",
            "judgeContent": {
                "judge": "Robert",
                "judged": "Karen"
            }
        }
    ]
}

// This is the desired deserialized object:

User(
    user_data = UserData(name = "Justin"),
    user_contributions = listOf(
        Mentor(
            id = "1",
            content = MentorContent(mentor = "Lisa", mentee = "Phil")
        ),
        Judge(
            id = "2",
            content = JudgeContent(judge = "Robert", judged = "Karen")
        )
    )
)