
### Environment

* Dubbo version: 2.7.4.1

### Steps to reproduce this issue

在dubbo正常启动的时候，会出现很多一样的警告
```
2020-03-11 22:56:34.344 [Finalizer] [WARN] com.alibaba.dubbo.config.AbstractConfig -  [DUBBO] ReferenceConfig(null) is not DESTROYED when FINALIZE, dubbo version: 2.6.4, current host: 192.168.31.245
2020-03-11 22:56:34.345 [Finalizer] [WARN] com.alibaba.dubbo.config.AbstractConfig -  [DUBBO] ReferenceConfig(null) is not DESTROYED when FINALIZE, dubbo version: 2.6.4, current host: 192.168.31.245
2020-03-11 22:56:34.345 [Finalizer] [WARN] com.alibaba.dubbo.config.AbstractConfig -  [DUBBO] ReferenceConfig(null) is not DESTROYED when FINALIZE, dubbo version: 2.6.4, current host: 192.168.31.245
```
是从下面触发了finalize()方法发出，但是现在这个里面也已经没有做任何操作了，是不是可以把finalizerGuardian去掉了？
```
 private final Object finalizerGuardian = new Object() {
        @Override
        protected void finalize() throws Throwable {
            super.finalize();

            if (!ReferenceConfig.this.destroyed) {
                logger.warn("ReferenceConfig(" + url + ") is not DESTROYED when FINALIZE");

                /* don't destroy for now
                try {
                    ReferenceConfig.this.destroy();
                } catch (Throwable t) {
                        logger.warn("Unexpected err when destroy invoker of ReferenceConfig(" + url + ") in finalize method!", t);
                }
                */
            }
        }
    };
```

return (T) PROXY_FACTORY.getProxy(invoker, ProtocolUtils.isGeneric(generic));
    }
    /**
     * This method should be called right after the creation of this class's instance, before any property in other config modules is used.
     * Check each config modules are created properly and override their properties if necessary.
     */
    public void checkAndUpdateSubConfigs() {
        if (StringUtils.isEmpty(interfaceName)) {
            throw new IllegalStateException("<dubbo:reference interface=\"\" /> interface not allow null!");
        }
        completeCompoundConfigs(consumer);
        if (consumer != null) {
            if (StringUtils.isEmpty(registryIds)) {
                setRegistryIds(consumer.getRegistryIds());
            }
        }
        // 
        checkDefault();
        this.refresh();
        if (getGeneric() == null && getConsumer() != null) {
            setGeneric(getConsumer().getGeneric());
        }
        if (ProtocolUtils.isGeneric(generic)) {
            interfaceClass = GenericService.class;
        } else {
            try {
                interfaceClass = Class.forName(interfaceName, true, Thread.currentThread()
                        .getContextClassLoader());
            } catch (ClassNotFoundException e) {
                throw new IllegalStateException(e.getMessage(), e);