when a new connection was created on each request, the lnd node would stop responding after a few minutes and needed to be restarted when frequent requests were made.
add_invoice provides r_hash and not r_hash_str, and there isn't a simple way to convert r_hash to r_hash_str, so it just makes sense for everything to use r_hash so that you can actually check the status of your invoices.
…voice to use r_hash instead of r_hash_str.