when use etcd-3.4 with https ,confd has ERROR client: response is invalid json.

[gitbeyond]

$ /data/apps/opt/confd/confd --version
confd 0.16.0 (Git SHA: 7217b0ca, Go Version: go1.10.2)
[user1@myserver confd]$ /data/apps/opt/confd/confd -config-file confd.toml 
...
 /data/apps/opt/confd/confd[56888]: ERROR client: response is invalid json. The endpoint is probably not valid etcd cluster endpoint.
...

[user1@my-server confd]$ cat confd.toml 
backend = "etcd"
#client_cakeys = "/data/apps/config/etcd/ssl/etcd-root-ca-all.pem"
client_cakeys = "/data/apps/config/etcd/ssl/etcd-root-ca.pem"
client_cert = "/data/apps/config/etcd/ssl/etcd-client-ca.pem"
client_key = "/data/apps/config/etcd/ssl/etcd-client-ca-key.pem"
confdir = "/data/apps/config/confd"
log-level = "debug"
interval = 30
nodes = [
  "https://10.111.32.1:2379",
]
noop = false
scheme = "https"
watch = true

etcd info

# etcdctl endpoint health
https://10.111.32.1:2379 is healthy: successfully committed proposal: took = 18.186985ms
https://10.111.32.2:2379 is healthy: successfully committed proposal: took = 19.953428ms
https://10.111.32.3:2379 is healthy: successfully committed proposal: took = 20.095768ms
# etcdctl member list
90bd3178dd0a7942, started, etcd3, https://10.111.32.1:2380, https://172.16.27.6:2379, false
f674e4102d2cb7c2, started, etcd1, https://10.111.32.1:2380, https://172.16.27.4:2379, false
fb3d93d2bb979bb1, started, etcd2, https://10.111.32.1:2380, https://172.16.27.5:2379, false

[gitbeyond]

After setting backend to etcdv3, it returns to normal

backend = "etcdv3"