replace hardcode category root id number with Category THE_ROOT_ID const

Author: mhhansen

app/code/Magento/CatalogGraphQl/Model/Resolver/Products/DataProvider/CategoryTree.php

@@ -17,6 +17,7 @@
 use Magento\Catalog\Model\ResourceModel\Category\Collection;
 use Magento\Catalog\Model\ResourceModel\Category\CollectionFactory;
 use Magento\CatalogGraphQl\Model\AttributesJoiner;
+use Magento\Catalog\Model\Category;
 
 /**
  * Category tree data provider
@@ -96,7 +97,7 @@ public function getTree(ResolveInfo $resolveInfo, int $rootCategoryId) : array
         $level = $this->levelCalculator->calculate($rootCategoryId);
 
         // If root category is being filter, we've to remove first slash
-        if ($rootCategoryId == 1) {
+        if ($rootCategoryId == Category::TREE_ROOT_ID) {
             $regExpPathFilter = sprintf('.*%s/[/0-9]*$', $rootCategoryId);
         } else {
             $regExpPathFilter = sprintf('.*/%s/[/0-9]*$', $rootCategoryId);