composer.json

{
    "config": {
        "vendor-dir": "vendor",
        "prepend-autoloader": false
    },
    "autoload": {
        "psr-4": {
            "PaypalPPBTlib\\": "vendor/ppbtlib/src/",
            "PaypalAddons\\": "."
        },
        "classmap": [
          "classes/PaypalCapture.php",
          "classes/PaypalOrder.php",
          "classes/PaypalLog.php",
          "classes/PaypalVaulting.php",
          "classes/PaypalIpn.php",
          "controllers/front/abstract.php"
        ]
    },
    "scripts": {
        "pre-autoload-dump": [
            "if [ ${PPBTCLASSLIB_DEV_PATH} ]; then php ${PPBTCLASSLIB_DEV_PATH}/PPBTlib/refresh.php .; fi"
        ]
    },
    "require": {
      "paypal/paypal-checkout-sdk": " 1.*",
      "guzzlehttp/guzzle": "6.*",
      "paypal/rest-api-sdk-php": "1.*"
    }
}