Repository Pattern Mixed DTO

ProductDTO.kt

@Entity(tableName = "Product")
data class ProductDTO(
    @PrimaryKey                
    @ColumnInfo(name = "id")    
    @SerializedName("id")
    val id: String?,
    @ColumnInfo(name = "name")
    @SerializedName("name")
    val name: String?,
    @ColumnInfo(name = "nowPrice")
    @SerializedName("nowPrice")
    val nowPrice: Double?,
    @ColumnInfo(name = "wasPrice")
    @SerializedName("wasPrice")
    val wasPrice: Double?
)