> For clean Markdown content of this page, append .md to this URL. For the complete documentation index, see https://buildwithfern.com/learn/llms.txt. ## 0.37.0 **`(feat):`** The `additionalBodyParameters` request option (`[String: String]`) is now applied to requests; previously it was accepted but ignored. Add a new `additionalBodyProperties` request option (`[String: JSONValue]`) for sending non-string JSON values (booleans, numbers, arrays, objects, and `null`). Both are merged into the serialized JSON request body using wire-format keys, override generated fields on collision, and create a JSON body when the endpoint has none (except GET and HEAD requests, which are still sent without a body); `additionalBodyProperties` wins when both set the same key. Multipart and raw `Data` bodies are left unchanged. `JSONValue` now supports string, integer, float, boolean, array, and dictionary literals.