public function setData($key, $value){

        $key = $this->normalizeKeyName($key);

        if( isset($this->_data[$key]) ){
            if( $this->_data[$key] !== $value ){
                $this->_original[$key] = $this->_data[$key];
                $this->_changes[$key] = $value;
            }
        }else{
            $this->_changes[$key] = $value;
        }

        $this->_data[$key] = $value;

        return $this;
    }