pub fn set_default_user_agent(user_agent: impl Into<String>)Expand description
Sets the process-wide default user-agent for outbound requests.
Applies to subsequently created HttpClient values (those that do not set
their own via HttpClientBuilder::user_agent) and to the engine’s other
outbound token traffic that reads this default — the PKCE provider’s
token/refresh requests and the client-credentials injector. A per-client
user-agent still overrides it for that client.