Why a value cannot be the User-Agent, or undefined when it can: a blank value
(empty or whitespace only) is refused before the header-value rule. Only an absent
userAgent means the default; a blank one would otherwise be sent as is. The
CLI's --user-agent parser calls this too.
Why a value cannot be the User-Agent, or undefined when it can: a blank value (empty or whitespace only) is refused before the header-value rule. Only an absent
userAgentmeans the default; a blank one would otherwise be sent as is. The CLI's--user-agentparser calls this too.