f payment document types

Author: TheBlueMatt

lightning/src/blinded_path/payment.rs

@@ -576,6 +576,10 @@ pub enum PaymentContext {
 }
 impl PaymentContext {
 	/// Returns the additional payment metadata stored alongside this payment context, if any.
+	///
+	/// Payment metadata is stored as a map from a numeric key to an arbitrary byte array value.
+	/// This allows for several types of metadata to be stored attached to a single payment. In the
+	/// future some optional features of LDK may use some keys.
 	pub fn payment_metadata(&self) -> Option<&BTreeMap<u64, Vec<u8>>> {
 		match self {
 			Self::Bolt12Offer(Bolt12OfferContext { payment_metadata, .. })
@@ -615,6 +619,10 @@ pub struct Bolt12OfferContext {
 	/// needs to be "stored" by a payment recipient for their own internal use, provided back to
 	/// them with the payment.
 	///
+	/// Payment metadata is stored as a map from a numeric key to an arbitrary byte array value.
+	/// This allows for several types of metadata to be stored attached to a single payment. In the
+	/// future some optional features of LDK may use some keys.
+	///
 	/// Note that because this is included in the payment onion, its size must be tightly
 	/// constrained. More than a few hundred bytes and the payment will be entirely unpayable (with
 	/// limited routing options as size increases).
@@ -643,6 +651,10 @@ pub struct AsyncBolt12OfferContext {
 	/// needs to be "stored" by a payment recipient for their own internal use, provided back to
 	/// them with the payment.
 	///
+	/// Payment metadata is stored as a map from a numeric key to an arbitrary byte array value.
+	/// This allows for several types of metadata to be stored attached to a single payment. In the
+	/// future some optional features of LDK may use some keys.
+	///
 	/// Note that because this is included in the payment onion, its size must be tightly
 	/// constrained. More than a few hundred bytes and the payment will be entirely unpayable (with
 	/// limited routing options as size increases).
@@ -665,6 +677,10 @@ pub struct Bolt12RefundContext {
 	/// needs to be "stored" by a payment recipient for their own internal use, provided back to
 	/// them with the payment.
 	///
+	/// Payment metadata is stored as a map from a numeric key to an arbitrary byte array value.
+	/// This allows for several types of metadata to be stored attached to a single payment. In the
+	/// future some optional features of LDK may use some keys.
+	///
 	/// Note that because this is included in the payment onion, its size must be tightly
 	/// constrained. More than a few hundred bytes and the payment will be entirely unpayable (with
 	/// limited routing options as size increases).