code: public static IocContainer getInstance(String xmlClasspath) {
  
      if (xml2containerMap == null) {
        xml2containerMap = new HashMap<>();
      }
      SpringContainer container = xml2containerMap.get(xmlClasspath);
      if (container == null) {
        container = new SpringContainer(new ClassPathXmlApplicationContext(xmlClasspath));
        xml2containerMap.put(xmlClasspath, container);
      }
      return container;
    }
docs: This method gets the {@link IocContainer} for the given {@code xmlClasspath}.
  
  @param xmlClasspath is the classpath to the XML configuration.
  @return the requested container.