`sendpay_success`
A notification for topic `sendpay_success` is sent every time a sendpay
success(with `complete` status). The json is same as the return value of
command `sendpay`/`waitsendpay` when these cammand succeeds.
```json
{
"sendpay_success": {
"id": 1,
"payment_hash": "5c85bf402b87d4860f4a728e2e58a2418bda92cd7aea0ce494f11670cfbfb206",
"destination": "035d2b1192dfba134e10e540875d366ebc8bc353d5aa766b80c090b39c3a5d885d",
"msatoshi": 100000000,
"amount_msat": "100000000msat",
"msatoshi_sent": 100001001,
"amount_sent_msat": "100001001msat",
"created_at": 1561390572,
"status": "complete",
"payment_preimage": "9540d98095fd7f37687ebb7759e733934234d4f934e34433d4998a37de3733ee"
}
}
```
`sendpay` doesn't wait for the result of sendpay and `waitsendpay`
returns the result of sendpay in specified time or timeout, but
`sendpay_success` will always return the result anytime when sendpay
successes if is was subscribed.
07f85cbf72