hash static method
Returns the UUIDv5 string for userId under the fixed namespace.
Always returns canonical lowercase form (e.g.
cfbff0d1-9375-5685-968a-48ce8b50e3ad). The result is suitable for
passing as the id argument to qe_shard_upsert,
qe_shard_delete, etc.
Implementation
static String hash(String userId) {
assert(userId.isNotEmpty, 'PointIdHasher: userId must not be empty');
return _uuid.v5(_namespace, userId);
}