NatchezMiddleware

A middleware that adds the current span's kernel to outgoing requests, performs requests in a span called http4s-client-request, and adds the following fields to that span.

• "client.http.method" -> "GET", "PUT", etc.
• "client.http.uri" -> request URI
• "client.http.status_code" -> "200", "403", etc. // why is this a string?

A middleware that adds the following standard fields to the current span:

• "http.method" -> "GET", "PUT", etc.
• "http.url" -> request URI (not URL)
• "http.status_code" -> "200", "403", etc. // why is this a string?
• "error" -> true // only present in case of error

In addition the following non-standard fields are added in case of error:

• "error.message" -> Exception message
• "error.stacktrace" -> Exception stack trace as a multi-line string
• "cancelled" -> true // only present in case of cancellation