remove unused shutdownLock (#10010)

Motivation:

This is unused variable

Modification:

removed variable

Result:

Removes unused lock

Co-authored-by: phani254 <phani254@yahoo.com>

transport/src/main/java/io/netty/channel/socket/oio/OioServerSocketChannel.java

@@ -33,7 +33,6 @@
 import java.net.SocketTimeoutException;
 import java.util.List;
 import java.util.concurrent.locks.Lock;
-import java.util.concurrent.locks.ReentrantLock;
 
 /**
  * {@link ServerSocketChannel} which accepts new connections and create the {@link OioSocketChannel}'s for them.
@@ -60,7 +59,6 @@ private static ServerSocket newServerSocket() {
     }
 
     final ServerSocket socket;
-    final Lock shutdownLock = new ReentrantLock();
     private final OioServerSocketChannelConfig config;
 
     /**