fix:Fix init of `ServiceMapping` when metadata center uses nacos. (#1148)

diff --git a/dubbo-admin-server/src/main/java/org/apache/dubbo/admin/config/ConfigCenter.java b/dubbo-admin-server/src/main/java/org/apache/dubbo/admin/config/ConfigCenter.java
index 6a178d6..f27d3af 100644
--- a/dubbo-admin-server/src/main/java/org/apache/dubbo/admin/config/ConfigCenter.java
+++ b/dubbo-admin-server/src/main/java/org/apache/dubbo/admin/config/ConfigCenter.java
@@ -22,6 +22,7 @@
 import org.apache.dubbo.admin.registry.config.GovernanceConfiguration;
 import org.apache.dubbo.admin.registry.mapping.AdminMappingListener;
 import org.apache.dubbo.admin.registry.mapping.ServiceMapping;
+import org.apache.dubbo.admin.registry.mapping.impl.NacosServiceMapping;
 import org.apache.dubbo.admin.registry.mapping.impl.NoOpServiceMapping;
 import org.apache.dubbo.admin.registry.metadata.MetaDataCollector;
 import org.apache.dubbo.admin.service.impl.InstanceRegistryCache;
@@ -203,7 +204,11 @@
         MappingListener mappingListener = new AdminMappingListener(serviceDiscovery, instanceRegistryCache);
         serviceMapping = ExtensionLoader.getExtensionLoader(ServiceMapping.class).getExtension(metadataUrl.getProtocol());
         serviceMapping.addMappingListener(mappingListener);
-        serviceMapping.init(metadataUrl);
+        if (serviceMapping instanceof NacosServiceMapping) {
+            serviceMapping.init(registryUrl);
+        } else {
+            serviceMapping.init(metadataUrl);
+        }
         return serviceMapping;
     }