confused about file wrapper depends on protocol

[HYisen]

netty-in-action/chapter12/src/main/java/nia/chapter12/HttpRequestHandler.java

Lines 63 to 68 in 68e95e2

	if (ctx.pipeline().get(SslHandler.class) == null) {
	ctx.write(new DefaultFileRegion(
	file.getChannel(), 0, file.length()));
	} else {
	ctx.write(new ChunkedNioFile(file.getChannel()));
	}

ctx.pipeline().get(SslHandler.class) == null checks whether HTTPS is enabled.
The difference between new DefaultFileRegion(file.getChannel(), 0, file.length()) and new ChunkedNioFile((file.getChannel())) is that the previous one would use zero-copy optimization, which is beneficial to performance if possible.
But how shall the protocol(TLS or not) determine the usage of optimization?