code: protected function makeSoapClientOptions()
      {
          $options = $this->soapClientOptions;
          $options['classmap'] = array_merge(Classmap::$soapheader4map, Classmap::$map);
  
          if (!empty($this->params->soapClientOptions)) {
              $options = array_merge($options, $this->params->soapClientOptions);
          }
  
          return $options;
      }
docs: Make SoapClient options for Soap Header 4 handler
  
  @return array