Fatal error: Uncaught Error: Interface "SellingPartnerApi\Contract\RequestSignerContract" not found in /home/amzgreatvaluesto/public_html/amz_sp/vendor/jlevers/selling-partner-api/lib/Authentication.php:14 Stack trace: #0 {main} thrown in /home/amzgreatvaluesto/public_html/amz_sp/vendor/jlevers/selling-partner-api/lib/Authentication.php on line 14