MAGETWO-57227: Payments configuration sections default setting are wrong

Author: iivashchenko

app/code/Magento/Paypal/etc/adminhtml/system.xml

@@ -28,12 +28,12 @@
             <group id="other_paypal_payment_solutions" translate="label" sortOrder="3" showInDefault="1" showInWebsite="1" showInStore="1">
                 <label>Other PayPal Payment Solutions:</label>
                 <fieldset_css>paypal-top-section paypal-other-header</fieldset_css>
-                <frontend_model>Magento\Paypal\Block\Adminhtml\System\Config\Fieldset\Expanded</frontend_model>
+                <frontend_model>\Magento\Config\Block\System\Config\Form\Fieldset</frontend_model>
             </group>
             <group id="other_payment_methods" translate="label" sortOrder="4" showInDefault="1" showInWebsite="1" showInStore="1">
                 <label>Other Payment Methods:</label>
                 <fieldset_css>paypal-top-section payments-other-header</fieldset_css>
-                <frontend_model>Magento\Paypal\Block\Adminhtml\System\Config\Fieldset\Expanded</frontend_model>
+                <frontend_model>\Magento\Config\Block\System\Config\Form\Fieldset</frontend_model>
             </group>
         </section>
         <section id="payment_all_paypal" showInDefault="0" showInWebsite="0" showInStore="0">

app/code/Magento/Paypal/view/adminhtml/web/styles.css

@@ -30,4 +30,6 @@
 .paypal-other-header > .admin__collapsible-block > a.open::before {content: "\25B2" !important;}
 .paypal-other-header > .admin__collapsible-block > a::before {color: #000; content: "\25BC" !important; font-size: 1rem; top: 2.2rem;}
 .paypal-other-header > .admin__collapsible-block > a {color: #007bdb !important; text-align: right;}
-.payments-other-header > .admin__collapsible-block > a::before {content: "" !important;}
+.payments-other-header > .admin__collapsible-block > a {display: inline-block;}
+.payments-other-header > .admin__collapsible-block > a::before {content: "\25BC" !important; font-size: 1rem;}
+.payments-other-header > .admin__collapsible-block > a.open::before {content: "\25B2" !important;}

dev/tests/integration/testsuite/Magento/Paypal/Model/Config/Structure/Reader/_files/actual/config.xml

@@ -28,12 +28,12 @@
             <group id="other_paypal_payment_solutions" translate="label" sortOrder="3" showInDefault="1" showInWebsite="1" showInStore="1">
                 <label>Other PayPal Payment Solutions:</label>
                 <fieldset_css>paypal-top-section paypal-other-header</fieldset_css>
-                <frontend_model>Magento\Paypal\Block\Adminhtml\System\Config\Fieldset\Expanded</frontend_model>
+                <frontend_model>\Magento\Config\Block\System\Config\Form\Fieldset</frontend_model>
             </group>
             <group id="other_payment_methods" translate="label" sortOrder="4" showInDefault="1" showInWebsite="1" showInStore="1">
                 <label>Other Payment Methods:</label>
                 <fieldset_css>paypal-top-section payments-other-header</fieldset_css>
-                <frontend_model>Magento\Paypal\Block\Adminhtml\System\Config\Fieldset\Expanded</frontend_model>
+                <frontend_model>\Magento\Config\Block\System\Config\Form\Fieldset</frontend_model>
             </group>
         </section>
         <section id="payment_all_paypal" showInDefault="0" showInWebsite="0" showInStore="0">

dev/tests/integration/testsuite/Magento/Paypal/Model/Config/Structure/Reader/_files/expected/config.xml

@@ -28,12 +28,12 @@
             <group id="other_paypal_payment_solutions" translate="label" sortOrder="3" showInDefault="1" showInWebsite="1" showInStore="1">
                 <label>Other PayPal Payment Solutions:</label>
                 <fieldset_css>paypal-top-section paypal-other-header</fieldset_css>
-                <frontend_model>Magento\Paypal\Block\Adminhtml\System\Config\Fieldset\Expanded</frontend_model>
+                <frontend_model>\Magento\Config\Block\System\Config\Form\Fieldset</frontend_model>
             </group>
             <group id="other_payment_methods" translate="label" sortOrder="4" showInDefault="1" showInWebsite="1" showInStore="1">
                 <label>Other Payment Methods:</label>
                 <fieldset_css>paypal-top-section payments-other-header</fieldset_css>
-                <frontend_model>Magento\Paypal\Block\Adminhtml\System\Config\Fieldset\Expanded</frontend_model>
+                <frontend_model>\Magento\Config\Block\System\Config\Form\Fieldset</frontend_model>
             </group>
         </section>
         <section id="payment_all_paypal" showInDefault="0" showInWebsite="0" showInStore="0">