Update Save.php

This keeps the form data persistent when the an Integration Exception is throw as a case when name of Integration being added is same.

Author: Aditya Yadav

app/code/Magento/Integration/Controller/Adminhtml/Integration/Save.php

@@ -74,7 +74,7 @@ public function execute()
             $this->_redirectOnSaveError();
         } catch (IntegrationException $e) {
             $this->messageManager->addError($this->escaper->escapeHtml($e->getMessage()));
-            $this->_getSession()->setIntegrationData($integrationData);
+            $this->_getSession()->setIntegrationData($this->getRequest()->getPostValue());
             $this->_redirectOnSaveError();
         } catch (\Magento\Framework\Exception\LocalizedException $e) {
             $this->messageManager->addError($this->escaper->escapeHtml($e->getMessage()));