code: @SuppressWarnings("unchecked")
  	public <T> T toObject(String jsonString, JavaType javaType) {
  		if (StringUtils.isEmpty(jsonString)) {
  			return null;
  		}
  
  		try {
  			return (T) mapper.readValue(jsonString, javaType);
  		} catch (IOException e) {
  			throw new RuntimeException(e);
  		}
  	}
docs: 反序列化复杂Collection如List<Bean>, 先使用函數createCollectionType构造类型,然后调用本函数.
  @see #createCollectionType(Class, Class...)