-/// payable HTLCs except for spontaneous payments, i.e. this should generally only be used for
-/// calls to [`ChannelManager::send_spontaneous_payment`].
+/// payable HTLCs except for single-path spontaneous payments, i.e. this should generally
+/// only be used for calls to [`ChannelManager::send_spontaneous_payment`]. If you are sending
+/// a spontaneous MPP this will not work as all MPP require payment secrets; you may
+/// instead want to use [`RecipientOnionFields::secret_only`].