Changing value for variable

1

Hello everybody!
I’m having a hard time on how to have a URL in a variable within the JSON.
For example, I have this data below:

“workflowApiVersion”: “1.1”,
“configurationArguments”: {
“applicationExtensionKey”: “”,
“save”: {
“url”: “http://example.com/”,
“verb”: “POST”,
“body”: “”,
“useJwt”: true
}
}

I would like to get the result below:

“workflowApiVersion”: “1.1”,
“configurationArguments”: {
“applicationExtensionKey”: “”,
“save”: {
“url”: “VARIABLE”,
“verb”: “POST”,
“body”: “”,
“useJwt”: true
}
}

Please could someone help me?
Thank you in advance.