MAGETWO-37819: Sales Tax Report doesn't work

Author: slopukhov

app/code/Magento/Sales/Model/Resource/Report/Order/Collection.php

@@ -104,13 +104,14 @@ protected function _getSelectedColumns()
     /**
      * Apply custom columns before load
      *
-     * @return void
+     * @return $this
      */
     protected function _beforeLoad()
     {
         $this->getSelect()->from($this->getResource()->getMainTable(), $this->_getSelectedColumns());
         if (!$this->isTotals()) {
             $this->getSelect()->group($this->_periodFormat);
         }
+        return parent::_beforeLoad();
     }
 }

app/code/Magento/Sales/Model/Resource/Report/Refunded/Collection/Order.php

@@ -85,13 +85,14 @@ protected function _getSelectedColumns()
     /**
      * Apply custom columns before load
      *
-     * @return void
+     * @return $this
      */
     protected function _beforeLoad()
     {
         $this->getSelect()->from($this->getResource()->getMainTable(), $this->_getSelectedColumns());
         if (!$this->isTotals()) {
             $this->getSelect()->group($this->_periodFormat);
         }
+        return parent::_beforeLoad();
     }
 }

app/code/Magento/Sales/Model/Resource/Report/Shipping/Collection/Order.php

@@ -89,7 +89,7 @@ protected function _getSelectedColumns()
     /**
      * Apply custom columns before load
      *
-     * @return void
+     * @return $this
      */
     protected function _beforeLoad()
     {
@@ -101,5 +101,6 @@ protected function _beforeLoad()
         if ($this->isSubTotals()) {
             $this->getSelect()->group([$this->_periodFormat]);
         }
+        return parent::_beforeLoad();
     }
 }

app/code/Magento/Tax/Model/Resource/Report/Collection.php

@@ -87,7 +87,7 @@ protected function _getSelectedColumns()
     /**
      * Apply custom columns before load
      *
-     * @return void
+     * @return $this
      */
     protected function _beforeLoad()
     {
@@ -99,5 +99,6 @@ protected function _beforeLoad()
         if ($this->isSubTotals()) {
             $this->getSelect()->group([$this->_periodFormat]);
         }
+        return parent::_beforeLoad();
     }
 }