[BTP] How to use the refresh_token to get a new valid access_token

# url from XSUAA Service Key
@xsuaaUrl = {{$dotenv xsuaaUrl}}
# clientid from XSUAA Service Key
@xsuaaClientId = {{$dotenv xsuaaClientId}}
# clientsecret from XSUAA Service Key
@xsuaaClientSecret = {{$dotenv xsuaaClientSecret}}

#==================================================================#

### Get Access Token for Cloud Foundry using Grant Type Password with BTP default IdP 
# @name token_response
POST {{xsuaaUrl}}/oauth/token
Authorization: Basic {{xsuaaClientId}}:{{xsuaaClientSecret}}
Accept: application/json;charset=utf8
Content-Type: application/x-www-form-urlencoded

grant_type=password
&username={{$dotenv btp_username}}
&password={{$dotenv btp_password}}
&response_type=token

### Store access token and refresh token
@access_token = {{token_response.response.body.$.access_token}}
@refresh_token = {{token_response.response.body.$.refresh_token}}


### Use Refresh Token
# @name token_response
POST {{xsuaaUrl}}/oauth/token
Authorization: Basic {{xsuaaClientId}}:{{xsuaaClientSecret}}
Accept: application/json;charset=utf8
Content-Type: application/x-www-form-urlencoded

grant_type=refresh_token
&refresh_token={{refresh_token}}

### Store access token and refresh token
@access_token = {{token_response.response.body.$.access_token}}
@refresh_token = {{token_response.response.body.$.refresh_token}}