public function addAppData(string $key, $value = null): void
    {
        $this->_additionalAppData[$key] = $value;
    }
public function addAppData(string $key, $value = null): void
    {
        $this->_additionalAppData[$key] = $value;
    }
public function addAppData ( string $ key , $ value = null ) : void { $ this -> _additionalAppData [ $ key ] = $ value ; }
Adds additional data to the appData

@param string $key string key
@param mixed $value value
@return void
Adds additional data to the appData