To use the Google Spreadsheet connector, add the
<googlespreadsheet.init> element in your proxy configuration before use any other Google Spreadsheet operations. This
<googlespreadsheet.init> element used to authenticates the user using OAuth2 authentication to access the Google account which contains the spreadsheets. For more information on authorizing requests in Google Spreadsheets, see see https://developers.google.com/sheets/google-appsapi/spreadsheetsguides/authorizeauthorizing.
Follow the guide to set up the Google Spreadsheets and get credentials such as clientId, clientSecret, accessToken, refreshToken.