Pith - kiln
package com.vgmlr.kiln

import androidx.room.TypeConverter

class KilnConverters {
    @TypeConverter
    fun toIds(csv: String?): Set<Long> =
        csv?.split(',')?.mapNotNull(String::toLongOrNull)?.toSet() ?: emptySet()

    @TypeConverter
    fun fromIds(ids: Set<Long>): String = ids.sorted().joinToString(",")
}