code: protected function getFullFileName(Provider $provider)
      {
          $folder = $this->folder ? rtrim($this->folder, '/').'/' : '';
  
          if ($this->filename) {
              $filename = $this->filename;
          } else {
              $filename = md5(uniqid(microtime(true), true));
          }
  
          return $folder.$filename.'.'.$provider->getExtension();
      }
docs: Get the full filename.
  
  @param  \Rymanalu\LaravelSimpleUploader\Contracts\Provider  $provider
  @return string