Replace the immutable Collections.emptyList() with a new ArrayList<>() (#375)

Author: hui-cha

server/server/meta/src/main/java/com/alipay/sofa/registry/server/meta/bootstrap/MetaServerBootstrap.java

@@ -41,19 +41,20 @@
 import com.github.rholder.retry.StopStrategies;
 import com.github.rholder.retry.WaitStrategies;
 import com.google.common.base.Predicate;
-import java.lang.annotation.Annotation;
-import java.util.*;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicBoolean;
-import javax.annotation.Resource;
-import javax.ws.rs.Path;
-import javax.ws.rs.ext.Provider;
 import org.apache.commons.collections.CollectionUtils;
 import org.apache.commons.lang.StringUtils;
 import org.glassfish.jersey.server.ResourceConfig;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.context.ApplicationContext;
 
+import javax.annotation.Resource;
+import javax.ws.rs.Path;
+import javax.ws.rs.ext.Provider;
+import java.lang.annotation.Annotation;
+import java.util.*;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
+
 /**
  * @author shangyu.wh
  * @version $Id: MetaServerBootstrap.java, v 0.1 2018-01-16 11:28 shangyu.wh Exp $
@@ -241,7 +242,7 @@ private void openSessionRegisterServer() {
         Collection<AbstractServerHandler> customSessionServerHandlers =
             this.customSessionServerHandlers();
         if (CollectionUtils.isNotEmpty(customSessionServerHandlers)) {
-          mergedSessionServerHandlers.addAll(this.customSessionServerHandlers());
+          mergedSessionServerHandlers.addAll(customSessionServerHandlers);
         }
 
         sessionServer =
@@ -267,7 +268,7 @@ private void openSessionRegisterServer() {
   }
 
   protected Collection<AbstractServerHandler> customSessionServerHandlers() {
-    return Collections.emptyList();
+    return new ArrayList<>();
   }
 
   private void openDataRegisterServer() {