Patch-Magento_Catalog-M2.2.x-skip-empty-custom-options-skus.patch

--- Model/Product/Option/Type/Select.php	2019-05-23 14:57:34.252542323 +0300
+++ Model/Product/Option/Type/Select.php	2019-05-23 15:12:41.468579643 +0300
@@ -268,7 +268,11 @@
             foreach (explode(',', $optionValue) as $value) {
                 $optionSku = $option->getValueById($value);
                 if ($optionSku) {
-                    $skus[] = $optionSku->getSku();
+                    // the fix to skip empty Custom Options SKUs and avoid adding extra delimiters to configurable product SKU [SPAR-148]
+                    $optionSkuValue = trim($optionSku->getSku());
+                    if($optionSkuValue) {
+                        $skus[] = $optionSkuValue;
+                    }
                 } else {
                     if ($this->getListener()) {
                         $this->getListener()->setHasError(true)->setMessage($this->_getWrongConfigurationMessage());