<Platform class kotlin.Unit requires explicit Json...

# stackoverflow

[user]

Platform class kotlin.Unit requires explicit JsonAdapter to be registered
In a retrofit interface I have defined a method return type as ApiModel . but when I call the method I get the error below.
Platform class kotlin.Unit requires explicit JsonAdapter to be registered

so I tried to create my own JsonAdapter as below.
class UnitJsonAdapter {

@ToJson
fun toJson(writer: JsonWriter) {
writer.nullValue()
}

@FromJson
fun fromJson(reader: JsonReader): Unit {
reader.close()
return Unit
}

}

but I face this error....