NioServerSocketChannel.isActive() must return false after close() completes. (#9030)

Motivation:

When a Channel was closed its isActive() method must return false.

Modifications:

First check for isOpen() before isBound() as isBound() will continue to return true even after the underyling fd was closed.

Result:

Fixes https://github.com/netty/netty/issues/9026.

transport/src/main/java/io/netty/channel/socket/nio/NioServerSocketChannel.java

@@ -106,7 +106,9 @@ public class NioServerSocketChannel extends AbstractNioMessageChannel
 
     @Override
     public boolean isActive() {
-        return javaChannel().socket().isBound();
+        // As java.nio.ServerSocketChannel.isBound() will continue to return true even after the channel was closed
+        // we will also need to check if it is open.
+        return isOpen() && javaChannel().socket().isBound();
     }
 
     @Override

transport/src/test/java/io/netty/channel/socket/nio/NioServerSocketChannelTest.java

@@ -15,6 +15,8 @@
  */
 package io.netty.channel.socket.nio;
 
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelFuture;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.nio.NioEventLoopGroup;
 import org.junit.Assert;
@@ -45,6 +47,23 @@ public class NioServerSocketChannelTest extends AbstractNioChannelTest<NioServer
         }
     }
 
+    @Test
+    public void testIsActiveFalseAfterClose()  {
+        NioServerSocketChannel serverSocketChannel = new NioServerSocketChannel();
+        EventLoopGroup group = new NioEventLoopGroup(1);
+        try {
+            group.register(serverSocketChannel).syncUninterruptibly();
+            Channel channel = serverSocketChannel.bind(new InetSocketAddress(0)).syncUninterruptibly().channel();
+            Assert.assertTrue(channel.isActive());
+            Assert.assertTrue(channel.isOpen());
+            channel.close().syncUninterruptibly();
+            Assert.assertFalse(channel.isOpen());
+            Assert.assertFalse(channel.isActive());
+        } finally {
+            group.shutdownGracefully();
+        }
+    }
+
     @Override
     protected NioServerSocketChannel newNioChannel() {
         return new NioServerSocketChannel();