protected function validateCSVHeaders($object, $attribute, $file)
    {
        $file = fopen($file->getTempName(), "r");
        $headerColumns = $this->explodeToColumns(fgets($file));
        if($headerColumns == array()) {
            $this->addError($object,$attribute,'Could not read header line. File empty? Make sure it uses: '.implode($this->separator,$this->columnNames));
        }
        if($headerColumns != $this->columnNames) {
            $this->addError($object,$attribute,'Wrong headers. Make sure the file uses: '.implode($this->separator,$this->columnNames));
        }
        fclose($file);
    }