public function addStatementToEntity(Statement $statement, ItemId $itemId, $baseRevisionId = null)
 {
     if ($this->currentItemId !== null && !$this->currentItemId->equals($itemId)) {
         $this->saveStatements();
     }
     $this->currentItemId = $itemId;
     $this->currentBaseRevisionId = $baseRevisionId;
     $this->statements[] = $statement;
 }