使用新的REST API应用程序从经典（IPN端点）搜索Paypal交易

I've been using PayPal's IPN to handle transactions. I wanted to build a invoice search tool to be able to search through older or current user payments for various reasons. I spent some time today setting up the PayPal PHP REST API SDK to facilitate this and did the following. I've been using PayPal's IPN to handle transact