code: @Override
      protected void initializeImpl()
      {
          String value=this.getConfigurationValue(FaxClientSpiConfigurationConstants.HTTP_CLIENT_CLASS_NAME_PROPERTY_KEY);
          if(value==null)
          {
              value=ApacheHTTPClient.class.getName();
          }
  
          //create HTTP client
          this.httpClient=(HTTPClient)ReflectionHelper.createInstance(value);
          
          //create configuration
          this.httpClientConfiguration=this.createHTTPClientConfiguration();
  
          //create fax job to HTTP request converter
          this.faxJob2HTTPRequestConverter=this.createFaxJob2HTTPRequestConverter();
  
          //create HTTP response handler
          this.httpResponseHandler=this.createHTTPResponseHandler();
  
          //get resources
          Map<FaxActionType,String> map=this.initializeFaxActionType2ResourceMap();
          this.faxActionType2ResourceMap=new HashMap<FaxActionType,String>(map);
          
          //get URL parameters
          this.urlParameters=this.initializeURLParameters();
      }
docs: This function initializes the fax client SPI.