### 问题
在测试新发布的3.0.1时，如果给dubbo.provider.delay指定值实现延迟暴露时，启动时会报空指针异常。

### 环境
* Dubbo version: 3.0.1
* Operating System version: win10
* Java version: 1.8.0_201

### 核心代码

1. maven 依赖文件
```
    <properties>
        <spring-boot.version>2.3.0.RELEASE</spring-boot.version>
        <dubbo.version>3.0.1</dubbo.version>
        <nacos-client.version>2.0.1</nacos-client.version>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo-spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.dubbo</groupId>
            <artifactId>dubbo-registry-nacos</artifactId>
        </dependency>
        <dependency>
            <groupId>com.alibaba.nacos</groupId>
            <artifactId>nacos-client</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
        </dependency>
    </dependencies>

    <dependencyManagement>
        <dependencies>
            <!-- Apache Dubbo  -->
            <dependency>
                <groupId>org.apache.dubbo</groupId>
                <artifactId>dubbo-dependencies-bom</artifactId>
                <version>${dubbo.version}</version>
                <type>pom</type>
                <scope>compile</scope>
            </dependency>

            <!-- Dubbo Registry Nacos -->
            <dependency>
                <groupId>org.apache.dubbo</groupId>
                <artifactId>dubbo-registry-nacos</artifactId>
                <version>${dubbo.version}</version>
                <scope>compile</scope>
            </dependency>

            <dependency>
                <groupId>com.alibaba.nacos</groupId>
                <artifactId>nacos-client</artifactId>
                <version>${nacos-client.version}</version>
                <scope>compile</scope>
            </dependency>


            <!-- Dubbo Spring Boot Starter -->
            <dependency>
                <groupId>org.apache.dubbo</groupId>
                <artifactId>dubbo-spring-boot-starter</artifactId>
                <version>${dubbo.version}</version>
                <scope>compile</scope>
            </dependency>

            <dependency>
                <groupId>org.apache.dubbo</groupId>
                <artifactId>dubbo</artifactId>
                <version>${dubbo.version}</version>
                <scope>compile</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
```
2. application.properties配置
```
dubbo.application.name=dubbo-provider
dubbo.registry.address=nacos://127.0.0.1:8848
dubbo.registry.check=false
dubbo.registry.username=nacos
dubbo.registry.password=nacos
dubbo.provider.delay=5000
dubbo.consumer.check=false
dubbo.metadata-report.address=nacos://127.0.0.1:8848
dubbo.metadata-report.username=nacos
dubbo.metadata-report.password=nacos
dubbo.protocol.name=dubbo
dubbo.protocol.port=20885
dubbo.protocol.threadpool=fixed
dubbo.protocol.threads=500
dubbo.version=1.0.0
```

3. 启动报空指针
>java.lang.NullPointerException: null
>	at org.apache.dubbo.registry.client.metadata.ServiceInstanceMetadataUtils.getMetadataServiceParameter(ServiceInstanceMetadataUtils.java:115) ~[dubbo-3.0.1.jar:3.0.1]
>	at org.apache.dubbo.registry.client.metadata.MetadataServiceURLParamsMetadataCustomizer.resolveMetadataPropertyValue(MetadataServiceURLParamsMetadataCustomizer.java:51) ~[dubbo-3.0.1.jar:3.0.1]
>	at org.apache.dubbo.registry.client.metadata.MetadataServiceURLParamsMetadataCustomizer.customize(MetadataServiceURLParamsMetadataCustomizer.java:38) ~[dubbo-3.0.1.jar:3.0.1]
>	at org.apache.dubbo.registry.client.metadata.ServiceInstanceMetadataUtils.lambda$customizeInstance$2(ServiceInstanceMetadataUtils.java:285) ~[dubbo-3.0.1.jar:3.0.1]
>	at java.lang.Iterable.forEach(Iterable.java:75) ~[na:1.8.0_201]
>	at org.apache.dubbo.registry.client.metadata.ServiceInstanceMetadataUtils.customizeInstance(ServiceInstanceMetadataUtils.java:283) ~[dubbo-3.0.1.jar:3.0.1]
>	at org.apache.dubbo.config.bootstrap.DubboBootstrap.createServiceInstance(DubboBootstrap.java:1432) ~[dubbo-3.0.1.jar:3.0.1]
>	at org.apache.dubbo.config.bootstrap.DubboBootstrap.registerServiceInstance(DubboBootstrap.java:1373) ~[dubbo-3.0.1.jar:3.0.1]
>	at org.apache.dubbo.config.bootstrap.DubboBootstrap.start(DubboBootstrap.java:1103) ~[dubbo-3.0.1.jar:3.0.1]
>	at org.apache.dubbo.config.spring.context.DubboBootstrapApplicationListener.onContextRefreshedEvent(DubboBootstrapApplicationListener.java:80) ~[dubbo-3.0.1.jar:3.0.1]
>	at org.apache.dubbo.config.spring.context.DubboBootstrapApplicationListener.onApplicationContextEvent(DubboBootstrapApplicationListener.java:72) ~[dubbo-3.0.1.jar:3.0.1]
>	at com.alibaba.spring.context.OnceApplicationContextEventListener.onApplicationEvent(OnceApplicationContextEventListener.java:52) ~[spring-context-support-1.0.8.jar:na]
>	at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:176) ~[spring-context-5.3.5.jar:5.3.5]
>	at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:169) ~[spring-context-5.3.5.jar:5.3.5]
>	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:143) ~[spring-context-5.3.5.jar:5.3.5]
>	at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:421) ~[spring-context-5.3.5.jar:5.3.5]
>	at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:378) ~[spring-context-5.3.5.jar:5.3.5]
>	at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:938) ~[spring-context-5.3.5.jar:5.3.5]
>	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586) ~[spring-context-5.3.5.jar:5.3.5]
>	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:144) ~[spring-boot-2.4.4.jar:2.4.4]
>	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:769) [spring-boot-2.4.4.jar:2.4.4]
>	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:761) [spring-boot-2.4.4.jar:2.4.4]
>	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:426) [spring-boot-2.4.4.jar:2.4.4]
>	at org.springframework.boot.SpringApplication.run(SpringApplication.java:326) [spring-boot-2.4.4.jar:2.4.4]
>	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1313) [spring-boot-2.4.4.jar:2.4.4]
>	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1302) [spring-boot-2.4.4.jar:2.4.4]
>	at cn.liyuguo.user.StartService.main(StartService.java:12) [classes/:na]

同样的配置，在2.7.11中，运行是正常的，如果配置方式已调整，请帮忙指出新的配置方法。
private final Logger logger = LoggerFactory.getLogger(getClass());
    private final MetadataService metadataService;
    private volatile ServiceConfig<MetadataService> serviceConfig;
    public ConfigurableMetadataServiceExporter(MetadataService metadataService) {
        this.metadataService = metadataService;
    }
    @Override
    public ConfigurableMetadataServiceExporter export() {
        if (!isExported()) {
            ServiceConfig<MetadataService> serviceConfig = new ServiceConfig<>();
            serviceConfig.setApplication(getApplicationConfig());
            serviceConfig.setRegistry(new RegistryConfig("N/A"));