⏫ Forwardport of #11274 to 2.3-develop branch

Applied pull request patch https://github.com/magento/magento2/pull/11274.patch (created by @marinagociu) based on commit(s):
  1. ae9f205
  2. f6121da

Fixed GitHub Issues in 2.3-develop branch:
  - #10477: Cart price rule has failed if use dropdown attribute (reported by @minosss)

app/code/Magento/SalesRule/Model/Rule/Condition/Product/Subselect.php

@@ -136,6 +136,7 @@ public function asHtml()
      *
      * @param \Magento\Framework\Model\AbstractModel $model
      * @return bool
+     * @SuppressWarnings(PHPMD.CyclomaticComplexity)
      */
     public function validate(\Magento\Framework\Model\AbstractModel $model)
     {
@@ -145,8 +146,22 @@ public function validate(\Magento\Framework\Model\AbstractModel $model)
         $attr = $this->getAttribute();
         $total = 0;
         foreach ($model->getQuote()->getAllVisibleItems() as $item) {
-            if (parent::validate($item)) {
-                $total += $item->getData($attr);
+            $hasValidChild = false;
+            $useChildrenTotal = ($item->getProductType() == \Magento\Catalog\Model\Product\Type::TYPE_BUNDLE);
+            $childrenAttrTotal = 0;
+            $children = $item->getChildren();
+            if (!empty($children)) {
+                foreach ($children as $child) {
+                    if (parent::validate($child)) {
+                        $hasValidChild = true;
+                        if ($useChildrenTotal) {
+                            $childrenAttrTotal += $child->getData($attr);
+                        }
+                    }
+                }
+            }
+            if ($hasValidChild || parent::validate($item)) {
+                $total += (($hasValidChild && $useChildrenTotal) ? $childrenAttrTotal : $item->getData($attr));
             }
         }
         return $this->validateAttribute($total);