add ability to use RoundRobinDnsAddressResolverGroup in Connection manager.

redisson/src/main/java/org/redisson/config/Config.java

@@ -598,10 +598,14 @@ public class Config {
         return keepPubSubOrder;
     }
 
+    /**
+     * Used to switch between {@link io.netty.resolver.dns.DnsAddressResolverGroup} implementations.
+     * Switch to round robin {@link io.netty.resolver.dns.RoundRobinDnsAddressResolverGroup} when you need to optimize the url resolving.
+     * @param addressResolverGroupFactory
+     */
     public void setAddressResolverGroupFactory(AddressResolverGroupFactory addressResolverGroupFactory) {
         this.addressResolverGroupFactory = addressResolverGroupFactory;
     }
-
     public AddressResolverGroupFactory getAddressResolverGroupFactory() {
         return addressResolverGroupFactory;
     }

redisson/src/main/java/org/redisson/connection/AddressResolverGroupFactory.java

@@ -11,6 +11,17 @@ import io.netty.resolver.dns.RoundRobinDnsAddressResolverGroup;
 public interface AddressResolverGroupFactory {
     DnsAddressResolverGroup create(Class<? extends DatagramChannel> channelType, DnsServerAddressStreamProvider nameServerProvider);
 
-    AddressResolverGroupFactory ROUND_ROBIN_DNS_ADDRESS_RESOLVER_GROUP = RoundRobinDnsAddressResolverGroup::new;
-    AddressResolverGroupFactory DNS_ADDRESS_RESOLVER_GROUP = DnsAddressResolverGroup::new;
+    AddressResolverGroupFactory ROUND_ROBIN_DNS_ADDRESS_RESOLVER_GROUP = new AddressResolverGroupFactory() {
+        @Override
+        public DnsAddressResolverGroup create(Class<? extends DatagramChannel> channelType, DnsServerAddressStreamProvider nameServerProvider) {
+            return new RoundRobinDnsAddressResolverGroup(channelType, nameServerProvider);
+        }
+    };
+
+    AddressResolverGroupFactory DNS_ADDRESS_RESOLVER_GROUP = new AddressResolverGroupFactory() {
+        @Override
+        public DnsAddressResolverGroup create(Class<? extends DatagramChannel> channelType, DnsServerAddressStreamProvider nameServerProvider) {
+            return new DnsAddressResolverGroup(channelType, nameServerProvider);
+        }
+    };
 }