docs: public static BeanBox getUniqueBeanBox(BeanBoxContext ctx, Class<?> clazz) {
  		BeanBoxException.assureNotNull(clazz, "Target class can not be null");
  		BeanBox box = ctx.beanBoxMetaCache.get(clazz);
  		if (box != null)
  			return box;
  		if (BeanBox.class.isAssignableFrom(clazz))
  			try {
  				box = (BeanBox) clazz.newInstance();
  				if (box.singleton == null)
  					box.singleton = true;
  			} catch (Exception e) {
  				BeanBoxException.throwEX(e);
  			}
  		else
  			box = doCreateBeanBox(ctx, clazz);
  		ctx.beanBoxMetaCache.put(clazz, box);
  		return box;
  	}