Fixing issue with webform value not submitted

src/Plugin/WebformElement/BootstrapDateTime.php

@@ -109,6 +109,9 @@ class BootstrapDateTime extends DateBase {
         $element['#default_value'] = ($element['#default_value']) ? DrupalDateTime::createFromTimestamp(strtotime($element['#default_value'])) : NULL;
       }
     }
+    if ($element['#type'] == 'bootstrap_date_time') {
+        $element['#default_value'] = ($element['#default_value']) ? DrupalDateTime::createFromTimestamp(strtotime($element['#default_value'])) : NULL;
+    }
   }
 
 
@@ -391,4 +394,24 @@ class BootstrapDateTime extends DateBase {
     $date_formatter = \Drupal::service('date.formatter');
     return $date_formatter->format($timestamp ?: \Drupal::time()->getRequestTime(), 'custom', $custom_format);
   }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function parseInputFormat(array &$element, $property) {
+    if (!isset($element[$property])) {
+      return;
+    }
+    elseif (is_array($element[$property])) {
+      foreach ($element[$property] as $key => $value) {
+        $timestamp = strtotime($value);
+        $element[$property][$key] = ($timestamp !== FALSE) ? $this->dateFormatter->format($timestamp, 'html_' . $this->getDateType($element)) : NULL;
+      }
+    }
+    else {
+      $timestamp = strtotime($element[$property]);
+      $element[$property] = ($timestamp !== FALSE) ? $this->dateFormatter->format($timestamp, 'custom', 'Y-m-d H:i' ) : NULL;
+    }
+  }
+
 }