empty response header values listed with : in header name

[jsoref]

Describe the bug
HTTP Response headers with empty values have their header name listed with a trailing :

To Reproduce

1. Run the following in a sh friendly shell with a cooperative nc:

   echo -e "HTTP/1.1 200 OK\nX-Foo:\nContent-Type: text/plain\n\n$(date)" | nc -l 1500

2. Open Insomnia
3. Make a new request
4. Set the request to (GET) http://localhost:1500
5. Click Send
6. Activate the Header response tab

See:

NAME	VALUE
X-Foo:
Content-Type	text/plain

Expected behavior

NAME	VALUE
X-Foo
Content-Type	text/plain

Screenshots

Desktop (please complete the following information):

• OS: macOS 11.4
• Installation Method: homebrew
• App Version 2021.4.0

Additional context
GitHub sends x-accepted-oauth-scopes: at times

[roguib]

I believe it could be an edge case, considering that an empty header value is not valid per RFC-7230. Don't know why Github sends x-accepted-oauth-scopes without any value though.

[jsoref]

Are you sure?

https://datatracker.ietf.org/doc/html/rfc7230#section-3.2.6

header-field   = field-name ":" OWS field-value OWS

field-name     = token
field-value    = *( field-content / obs-fold )

I'm pretty sure the * in the field-vaue definition effectively means optional.

[roguib]

Not 100% TBH. I did a quick research and some users were saying that empty header values were not valid unless some specific cases, since they could introduce security risks. It would be nice to know exactly if they are valid or not. Source. However, I found a StackOverflow answer saying that empty headers are valid if they don't contain any characters, so I'm quite confused if they're valid or not.

[jsoref]

The source you linked to includes a reference to mnot who should be taken as authoritative and it aligns with what I'm saying. He's a spec person. I'm a browser person. We agree.

I too am sorry that people have trouble reading specifications but this really isn't complicated. The ABNF isn't ambiguous and even the prose isn't terrible it says a field-value, and a field value is defined as a * of thing and that means the thing is optional.