code: private static JCorsConfig loadFromFileStream(InputStream fileStream) {
  
  		try {
  
  			JAXBContext context = JAXBContext.newInstance(ConfigBuilder.class);
  			
  			Unmarshaller unmarshaller = context.createUnmarshaller();
  			unmarshaller.setSchema(loadXmlSchema());
  
  			ConfigBuilder configBuilder = (ConfigBuilder) unmarshaller.unmarshal(fileStream);
  			Constraint.ensureNotNull(configBuilder, "It was not possible to get a valid configuration builder instance");
  
  			return configBuilder.buildConfig();
  
  		} catch (Exception e) {
  
  			log.error("Failed loading configuration file", e);
  			return null;
  		}
  
  	}
docs: Builds a configuration class based on XML file
  
  @param file
  @return