Adjust ChannelGroup to behave the same like a Channel in terms of write and flush

transport/src/main/java/io/netty/channel/group/ChannelGroup.java

@@ -103,10 +103,24 @@ public interface ChannelGroup extends Set<Channel>, Comparable<ChannelGroup> {
      * condition. Please note that this operation is asynchronous as
      * {@link Channel#write(Object)} is.
      *
+     * @return itself
+     */
+    ChannelGroup write(Object message);
+
+    /**
+     * Flush all {@link Channel}s in this
+     * group.  Please note that this operation is asynchronous as
+     * {@link Channel#flush()} is.
+     *
      * @return the {@link ChannelGroupFuture} instance that notifies when
      *         the operation is done for all channels
      */
-    ChannelGroupFuture write(Object message);
+    ChannelGroupFuture flush();
+
+    /**
+     * Shortcut for calling {@link #write(Object)} and {@link #flush()}.
+     */
+    ChannelGroupFuture flushAndWrite(Object message);
 
     /**
      * Disconnects all {@link Channel}s in this group from their remote peers.

transport/src/main/java/io/netty/channel/group/DefaultChannelGroup.java

@@ -192,17 +192,39 @@ public class DefaultChannelGroup extends AbstractSet<Channel> implements Channel
     }
 
     @Override
-    public ChannelGroupFuture write(Object message) {
+    public ChannelGroup write(Object message) {
         if (message == null) {
             throw new NullPointerException("message");
         }
 
-        Map<Channel, ChannelFuture> futures = new LinkedHashMap<Channel, ChannelFuture>(size());
         for (Channel c: nonServerChannels) {
-            futures.put(c, c.write(safeDuplicate(message)).flush());
+            c.write(safeDuplicate(message));
         }
 
         ReferenceCountUtil.release(message);
+        return this;
+    }
+
+    @Override
+    public ChannelGroupFuture flush() {
+        Map<Channel, ChannelFuture> futures = new LinkedHashMap<Channel, ChannelFuture>(size());
+        for (Channel c: nonServerChannels) {
+            futures.put(c, c.flush());
+        }
+
+        return new DefaultChannelGroupFuture(this, futures, executor);
+    }
+
+    @Override
+    public ChannelGroupFuture flushAndWrite(Object message) {
+        Map<Channel, ChannelFuture> futures = new LinkedHashMap<Channel, ChannelFuture>(size());
+
+        for (Channel c: nonServerChannels) {
+            futures.put(c, c.writeAndFlush(safeDuplicate(message)));
+        }
+
+        ReferenceCountUtil.release(message);
+
         return new DefaultChannelGroupFuture(this, futures, executor);
     }