Switching field group's frontend model to 'Payment' so the config-heading wrapper gets printed

etc/adminhtml/system/adyen_apple_pay.xml

@@ -24,7 +24,7 @@
 <include xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_include.xsd">
     <group id="adyen_apple_pay" translate="label" type="text" sortOrder="460" showInDefault="1" showInWebsite="1" showInStore="1">
         <label><![CDATA[Apple Pay integration]]></label>
-        <frontend_model>Magento\Paypal\Block\Adminhtml\System\Config\Fieldset\Group</frontend_model>
+        <frontend_model>Magento\Paypal\Block\Adminhtml\System\Config\Fieldset\Payment</frontend_model>
         <fieldset_css>adyen-method-adyen-cc</fieldset_css>
         <comment>Process Apple Pay transactions</comment>
         <field id="active" translate="label" type="select" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">