ENGCOM-4444: [Backport] Fixes for product tabbing issue #21588

 - Merge Pull Request #21588 from amol2jcommerce/magento2:2.2-develop-PR-port-21079
 - Merged commits:
   1. ab2de15
   2. c6c6ead
   3. 905085d
   4. 2d3a876

Author: magento-engcom-team

app/code/Magento/Catalog/Model/ResourceModel/Product/Indexer/Price/CustomOptionPriceModifier.php

@@ -127,6 +127,8 @@ public function modifyPrice(IndexTableStructure $priceTable, array $entityIds =
     }
 
     /**
+     * Check if custom options exist.
+     *
      * @param IndexTableStructure $priceTable
      * @return bool
      * @throws \Exception
@@ -154,6 +156,8 @@ private function checkIfCustomOptionsExist(IndexTableStructure $priceTable): boo
     }
 
     /**
+     * Get connection.
+     *
      * @return \Magento\Framework\DB\Adapter\AdapterInterface
      */
     private function getConnection()
@@ -211,7 +215,7 @@ private function getSelectForOptionsWithMultipleValues(string $sourceTable): Sel
         } else {
             $select->joinLeft(
                 ['otps' => $this->getTable('catalog_product_option_type_price')],
-                'otps.option_type_id = otpd.option_type_id AND otpd.store_id = cwd.default_store_id',
+                'otps.option_type_id = otpd.option_type_id AND otps.store_id = cwd.default_store_id',
                 []
             );
 
@@ -373,6 +377,8 @@ private function getSelectAggregated(string $sourceTable): Select
     }
 
     /**
+     * Get select for update.
+     *
      * @param string $sourceTable
      * @return \Magento\Framework\DB\Select
      */
@@ -402,6 +408,8 @@ private function getSelectForUpdate(string $sourceTable): Select
     }
 
     /**
+     * Get table name.
+     *
      * @param string $tableName
      * @return string
      */
@@ -411,6 +419,8 @@ private function getTable(string $tableName): string
     }
 
     /**
+     * Is price scope global.
+     *
      * @return bool
      */
     private function isPriceGlobal(): bool

app/code/Magento/Catalog/Model/ResourceModel/Product/Indexer/Price/DefaultPrice.php

@@ -10,6 +10,7 @@
 
 /**
  * Default Product Type Price Indexer Resource model
+ *
  * For correctly work need define product type id
  *
  * @api
@@ -208,6 +209,8 @@ public function reindexEntity($entityIds)
     }
 
     /**
+     * Reindex prices.
+     *
      * @param null|int|array $entityIds
      * @return \Magento\Catalog\Model\ResourceModel\Product\Indexer\Price\DefaultPrice
      */
@@ -604,7 +607,7 @@ protected function _applyCustomOption()
             []
         )->joinLeft(
             ['otps' => $this->getTable('catalog_product_option_type_price')],
-            'otps.option_type_id = otpd.option_type_id AND otpd.store_id = cs.store_id',
+            'otps.option_type_id = otpd.option_type_id AND otps.store_id = cs.store_id',
             []
         )->group(
             ['i.entity_id', 'i.customer_group_id', 'i.website_id', 'o.option_id']
@@ -802,6 +805,8 @@ public function getIdxTable($table = null)
     }
 
     /**
+     * Check if product exists.
+     *
      * @return bool
      */
     protected function hasEntity()
@@ -823,6 +828,8 @@ protected function hasEntity()
     }
 
     /**
+     * Get total tier price expression.
+     *
      * @param \Zend_Db_Expr $priceExpression
      * @return \Zend_Db_Expr
      */
@@ -862,6 +869,13 @@ private function getTotalTierPriceExpression(\Zend_Db_Expr $priceExpression)
         );
     }
 
+    /**
+     * Get tier price expression for table.
+     *
+     * @param string $tableAlias
+     * @param \Zend_Db_Expr $priceExpression
+     * @return \Zend_Db_Expr
+     */
     private function getTierPriceExpressionForTable($tableAlias, \Zend_Db_Expr $priceExpression)
     {
         return $this->getConnection()->getCheckSql(

app/code/Magento/Catalog/Pricing/Price/MinimalTierPriceCalculator.php

@@ -29,8 +29,10 @@ public function __construct(CalculatorInterface $calculator)
     }
 
     /**
-     * Get raw value of "as low as" as a minimal among tier prices
-     * {@inheritdoc}
+     * Get raw value of "as low as" as a minimal among tier prices{@inheritdoc}
+     *
+     * @param SaleableInterface $saleableItem
+     * @return float|null
      */
     public function getValue(SaleableInterface $saleableItem)
     {
@@ -49,15 +51,17 @@ public function getValue(SaleableInterface $saleableItem)
     }
 
     /**
-     * Return calculated amount object that keeps "as low as" value
-     * {@inheritdoc}
+     * Return calculated amount object that keeps "as low as" value{@inheritdoc}
+     *
+     * @param SaleableInterface $saleableItem
+     * @return AmountInterface|null
      */
     public function getAmount(SaleableInterface $saleableItem)
     {
         $value = $this->getValue($saleableItem);
 
         return $value === null
             ? null
-            : $this->calculator->getAmount($value, $saleableItem);
+            : $this->calculator->getAmount($value, $saleableItem, 'tax');
     }
 }