I am developing a framework that support Apache APISIX plugins run directly in Envoy Lua filter without modify Envoy. #13307

But in the process, I found that some header values, such as client IP and custom headers, cannot be get in Lua filter.

I think client IP and custom headers should be very commonly used.

I might misreading/misunderstanding, but I don't know how to get them, please remind me, thank you !