> For clean Markdown content of this page, append .md to this URL. For the complete documentation index, see https://buildwithfern.com/learn/llms.txt. ## 0.42.2 **`(fix):`** Endpoints now send API-, service- and endpoint-level headers whose types are literals (e.g. `Accept-Encoding: literal<"gzip">`). Previously these headers were silently dropped. Caller-supplied values via `RequestOptions::additional_header` still take precedence over the literal defaults.