code: public static boolean checkFunctionSwitch(Invoker<?> invoker, Invocation invocation){
          //先动态从调用地址里面获取开关配置信息，这个配置可以在配置中心的动态配置{methodName.}circuit.bread=true/false
          String circuitBreak = invoker.getUrl().getMethodParameter(invocation.getMethodName(),"circuit.break");
          if(StringUtils.isEmpty(circuitBreak)){
              String interfaceName = invoker.getUrl().getParameter(Constants.INTERFACE_KEY);
              String method = invocation.getMethodName();
              StringBuffer interfaceConfig = new StringBuffer(DUBBO_REFERENCE_PREFIX);
              interfaceConfig.append(interfaceName);
              StringBuffer methodConfig = new StringBuffer(interfaceConfig.toString());
              methodConfig.append(".").append(method);
              return getSwitch(interfaceConfig,methodConfig);
          }
          return Boolean.parseBoolean(StringUtils.trim(circuitBreak));
      }
docs: 获取当前调用的服务方法是否开启了服务降级功能
  @param invoker
  @param invocation
  @return