FEAT: retrieve custom http headers

[javens0601]

Retrieve custom HTTP request headers from extra param, so user can extend some custom logic
eg:
x_name = extra.requestInfo.headers['x-name'] as string

[zereight]

It would be helpful to provide a concrete example or use case for how custom HTTP headers are intended to be used in this context. Without a clear usage plan, it's difficult to evaluate the practical value and necessity of this change.