code: protected void initialiseApplicationContext() {
          if (context != null) {
              return;
          }
  
          context = createApplicationContext(parent);
  
          if (parent != null && classLoader == null) {
              trySettingClassLoaderOnContextIfFoundInParent(parent);
          }
          else if (classLoader != null) {
              setClassLoaderOnContext(classLoader);
          }
  
          Assert.notNull(context, "ApplicationContext cannot be null");
      }
docs: Initialises the ApplicationContext instance.