A restful auth problem

Hello Community,
I am develping a datasource plugin and I got a problem.
How can i get the auth result header ‘X-Subject-Token’ and set it to future request header ‘X-Auth-Token’?
The auth request is a http restful request with json body.The password is in secureJsonData filed which cannot get from plugin or browser.I saw the fllowing example, but grafana can automatically get ‘X-Subject-Token’ and set the value to ‘X-Auth-Token’?How to achieve this function?
“routes”: [
“path”: “azuremonitor”,
“method”: “GET”,
“url”: “https://management.azure.com”,
“tokenAuth”: {
“url”: “https://login.microsoftonline.com/{{.JsonData.tenantId}}/oauth2/token”,
“params”: {
“grant_type”: “client_credentials”,
“client_id”: “{{.JsonData.clientId}}”,
“client_secret”: “{{.SecureJsonData.clientSecret}}”,
“resource”: “https://management.azure.com/


Please see documentation.