ENGCOM-3286: Feature/import behavior improvement #139

 - Merge Pull Request magento-engcom/import-export-improvements#139 from sawebvisum/import-export-improvements:feature/importBehaviorImprovement
 - Merged commits:
   1. e5e5832
   2. 9c61729

Author: magento-engcom-team

app/code/Magento/ImportExport/Model/Import/Entity/AbstractEntity.php

@@ -554,7 +554,9 @@ public function getBehavior()
             $this->_parameters['behavior']
         ) ||
             $this->_parameters['behavior'] != ImportExport::BEHAVIOR_APPEND &&
+            $this->_parameters['behavior'] != ImportExport::BEHAVIOR_ADD_UPDATE &&
             $this->_parameters['behavior'] != ImportExport::BEHAVIOR_REPLACE &&
+            $this->_parameters['behavior'] != ImportExport::BEHAVIOR_CUSTOM &&
             $this->_parameters['behavior'] != ImportExport::BEHAVIOR_DELETE
         ) {
             return ImportExport::getDefaultBehavior();
@@ -828,6 +830,8 @@ public function validateData()
     }
 
     /**
+     * Get error aggregator object
+     *
      * @return ProcessingErrorAggregatorInterface
      */
     public function getErrorAggregator()