Update create_refund_builder to use create_blinded_paths

Aligned the `create_refund_builder` logic with
`create_offer_builder` by updating it to use `create_blinded_paths`.

Now that custom routers can be passed via
`create_refund_builder_using_router`, the default builder can
consistently generate full-length blinded paths without branching
logic.
This simplifies the default behavior while keeping flexibility
available for custom use cases.

Author: shaavan

lightning/src/ln/channelmanager.rs

@@ -10287,8 +10287,7 @@ macro_rules! create_refund_builder { ($self: ident, $builder: ty) => {
 	///
 	/// # Privacy
 	///
-	/// Uses [`MessageRouter`] to construct a [`BlindedMessagePath`] for the refund based on the given
-	/// `absolute_expiry` according to [`MAX_SHORT_LIVED_RELATIVE_EXPIRY`]. See those docs for
+	/// Uses [`MessageRouter`] to construct a [`BlindedMessagePath`] for the refund. See those docs for
 	/// privacy implications as well as those of the parameterized [`Router`], which implements
 	/// [`MessageRouter`].
 	///
@@ -10320,8 +10319,8 @@ macro_rules! create_refund_builder { ($self: ident, $builder: ty) => {
 		let secp_ctx = &$self.secp_ctx;
 
 		let nonce = Nonce::from_entropy_source(entropy);
-		let context = OffersContext::OutboundPayment { payment_id, nonce, hmac: None };
-		let path = $self.create_blinded_paths_using_absolute_expiry(context, Some(absolute_expiry))
+		let context = MessageContext::Offers(OffersContext::OutboundPayment { payment_id, nonce, hmac: None });
+		let path = $self.create_blinded_paths(context)
 			.and_then(|paths| paths.into_iter().next().ok_or(()))
 			.map_err(|_| Bolt12SemanticError::MissingPaths)?;
 

lightning/src/ln/offers_tests.rs

@@ -454,10 +454,11 @@ fn creates_short_lived_refund() {
 	let bob = &nodes[1];
 	let bob_id = bob.node.get_our_node_id();
 
+	let router = CompactMessageRouter::new(alice.network_graph, alice.node.entropy_source);
 	let absolute_expiry = bob.node.duration_since_epoch() + MAX_SHORT_LIVED_RELATIVE_EXPIRY;
 	let payment_id = PaymentId([1; 32]);
 	let refund = bob.node
-		.create_refund_builder(10_000_000, absolute_expiry, payment_id, Retry::Attempts(0), RouteParametersConfig::default())
+		.create_refund_builder_using_router(router, 10_000_000, absolute_expiry, payment_id, Retry::Attempts(0), RouteParametersConfig::default())
 		.unwrap()
 		.build().unwrap();
 	assert_eq!(refund.absolute_expiry(), Some(absolute_expiry));