class ConnectionUtil {

    public static Connection getConnectionFromChannel(Channel channel) {<FILL_FUNCTION_BODY>}

    public static void addIdPoolKeyMapping(Integer id, String group, Channel channel) {
        Connection connection = getConnectionFromChannel(channel);
        if (connection != null) {
            connection.addIdPoolKeyMapping(id, group);
        }
    }

    public static String removeIdPoolKeyMapping(Integer id, Channel channel) {
        Connection connection = getConnectionFromChannel(channel);
        if (connection != null) {
            return connection.removeIdPoolKeyMapping(id);
        }

        return null;
    }

    public static void addIdGroupCallbackMapping(Integer id, InvokeFuture callback, Channel channel) {
        Connection connection = getConnectionFromChannel(channel);
        if (connection != null) {
            connection.addInvokeFuture(callback);
        }
    }

    public static InvokeFuture removeIdGroupCallbackMapping(Integer id, Channel channel) {
        Connection connection = getConnectionFromChannel(channel);
        if (connection != null) {
            return connection.removeInvokeFuture(id);
        }
        return null;
    }

    public static InvokeFuture getGroupRequestCallBack(Integer id, Channel channel) {
        Connection connection = getConnectionFromChannel(channel);
        if (connection != null) {
            return connection.getInvokeFuture(id);
        }

        return null;
    }
}

        if (channel == null) {
            return null;
        }

        Attribute<Connection> connAttr = channel.attr(Connection.CONNECTION);
        if (connAttr != null) {
            Connection connection = connAttr.get();
            return connection;
        }
        return null;
    
<no_super_class>