If you face System.CalloutException: Method can not be null issue, make sure you are using POST Or GET Or PUT in your request suing setMethod().
HTTPRequest req = new HTTPRequest();
req.setEndPoint( 'End Point URL' );
req.setMethod( 'GET' );
If you face System.CalloutException: Method can not be null issue, make sure you are using POST Or GET Or PUT in your request suing setMethod().
HTTPRequest req = new HTTPRequest();
req.setEndPoint( 'End Point URL' );
req.setMethod( 'GET' );