@Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if (evt instanceof SslHandshakeCompletionEvent) {
            final SslHandler sslHandler = ctx.channel().pipeline().get(SslHandler.class);
            sslSession = sslHandler != null ? sslHandler.engine().getSession() : null;
            return;
        }

        if (evt instanceof SslCloseCompletionEvent ||
            evt instanceof ChannelInputShutdownReadComplete) {
            // Expected events
            return;
        }

        logger.warn("{} Unexpected user event: {}", ctx.channel(), evt);
    }
Sets the 'content-length' header to the response.
core/src/main/java/com/linecorp/armeria/server/HttpServerHandler.java