JSON automation rule for copying responder field values to Request Participant field

[SG]

I would like to copy value of "Responder" locked field to "Request Participant" locked field using JSON in automation but its not working. Any idea would be appreciated.

{
"update": {
},
"fields": {
"customfield_10176.Name": "{{issue.fields.customfield_10040.Name}}"
}
}

Reponder = 10176

Request Participant = 10040