When I configure VxLAN for an interface in the same way as I did, I get validation error.
Server Error : The server encountered an unexpected condition which prevented it from fulfilling the request. - : Failed to validate DataTreeModification
see log for more info.

I tried to set src IP to 10.0.10.1
which fits the specified regex:
(([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.)

{3}

([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])(%[\p

{N}

\p

{L}

]+)?

defined in ietf-inet-types.yang

Tests steps:
1. login to Honeycomb as admin
2. go to ietf-interfaces --> config --> interfaces
3. GET the current status
4. add VxLAN src address 10.0.10.1
5. PUT the configuration

Result:
The error is received, see above.

The request is generated by HC, I just fill the fields. The request shown by HC is as follows, the changed part is red:

http://10.0.0.5:8181/restconf/config/ietf-interfaces:interfaces
{
"interfaces": {
"interface": [
{
"name": "GigabitEthernet0/9/0",
"type": "iana-if-type:ethernetCsmacd",
"enabled": "false",
"ietf-ip:ipv6": {
"enabled": "true",
"forwarding": "true",
"mtu": "9000",
"neighbor": [

{ "ip": "10::11", "link-layer-address": "08:00:27:c0:5d:37" }

],
"dup-addr-detect-transmits": "5"
},
"v3po:ethernet":

{ "mtu": "9000" }

,
"v3po:routing":

{ "vrf-id": "27" }

,
* "v3po:vxlan": {
"src": "10.0.10.1"*
},
"v3po:l2":

{ "bridge-domain": "bd-01", "split-horizon-group": "1", "bridged-virtual-interface": "true" }

},
{
"name": "GigabitEthernet0/8/0",
"type": "iana-if-type:ethernetCsmacd",
"v3po:l2":

{ "bridge-domain": "bd-01", "bridged-virtual-interface": true, "split-horizon-group": 1 }

,
"enabled": false
},

{ "name": "local0", "enabled": false, "type": "iana-if-type:ethernetCsmacd" }

,

{ "name": "pg/stream-2", "enabled": false, "type": "iana-if-type:ethernetCsmacd" }

,

{ "name": "pg/stream-3", "enabled": false, "type": "iana-if-type:ethernetCsmacd" }

,

{ "name": "pg/stream-0", "enabled": false, "type": "iana-if-type:ethernetCsmacd" }

,
{
"name": "pg/stream-1",
"type": "iana-if-type:ethernetCsmacd",
"enabled": "true",
"ietf-ip:ipv4": {
"address": [

{ "ip": "10.0.10.3", "prefix-length": "24" }

]
},
"v3po:vxlan":

{ "src": "192.168.1.2" }

}
]
}
}