apollo-client/src/main/java/com/ctrip/framework/apollo/spring/property/SpringValue.java/SpringValue/SpringValue
class SpringValue:  public SpringValue(String key, String placeholder, Object bean, String beanName, Method method, boolean isJson) {
    this.beanRef = new WeakReference<>(bean);
    this.beanName = beanName;
    this.methodParameter = new MethodParameter(method, 0);
    this.key = key;
    this.placeholder = placeholder;
    Class<?>[] paramTps = method.getParameterTypes();
    this.targetType = paramTps[0];
    this.isJson = isJson;
    if(isJson){
      this.genericType = method.getGenericParameterTypes()[0];
    }
  }