Heuristics in isLSP

[btochi]

When estimating route fees through probing, the isLSP function is called to decided if the destination node is being serviced by a Lightning Service Provider. In such case, the probe is performed to the LSP.

The documentation of such function reads,

// isLSP checks if the route hints indicate an LSP. An LSP is indicated with
// true if the destination hop hint in each route hint has the same node id,
// false otherwise....

Muun Wallet invoices currently show 2 route hints with different node ids. Lightspark seems to have had a similar issue as reported in a comment. Evidently, several LSP use multiple public nodes to route payments to their users. Thus, the requirement that the last node id of each route hint is the same is too demanding. I strongly suggest not returning False in this case.

(since this was the intended behaviour of this function, I'm opening this as a discussion and not a bug report)