void addClosedEventListener(final ConnectionClosedEventListener listener) {
      this.ch.closeFuture() //
      .addListener(
          future -> listener.onClosed(this.ch.remoteAddress().toString(), NettyConnection.this));
    }
Get netty channel.

@author jiachun.fjc
jraft-extension/rpc-grpc-impl/src/main/java/io/grpc/netty/shaded/io/grpc/netty/NettyConnectionHelper.java