kotlin-simple-equals-and-hashcode.kt

fun hashCodeOf(vararg values: Any?): Int =
    values.fold(0) { acc, value ->
        (acc * 31) + value.hashCode()
    }
  
class Category(
    val id: Long? = null,
    val name: String,
    val createdAt: LocalDateTime? = null,
    val updatedAt: LocalDateTime? = null
) {
    override fun equals(other: Any?): Boolean = this === other ||
            other is Category &&
            id == other.id &&
            name == other.name &&
            createdAt == other.createdAt &&
            updatedAt == other.updatedAt

    override fun hashCode(): Int = hashCodeOf(id, name, createdAt, updatedAt)
}