as the title say cannot find the helper to validate payment
There was an issue with this in a previous version of the SDK but that has since been fixed. Are you using the latest version 30.0.0.20230816 of the SDK? 
yes i am using the latest version,and found the issue.
Its not importing properly, i am getting trait expected,class found message while hovering… also fyi i am using php 8. can you look into the issue? how can i import this class here
Is there any more details to your error message? All I could find around the class not found message was a composer error where they recommended composer dump-autoload.
thank sorry it was my mistake