Ошибка при внедрении комнаты

ошибка:

Entities and Pojos must have a usable public constructor. You can have an empty constructor or a constructor whose parameters match the fields (by name and type).  

Моя сущность

@Entity
data class Category(var category: String) {

@field: PrimaryKey(autoGenerate = true)
var categoryId: Int = 0


}