> For clean Markdown content of this page, append .md to this URL. For the complete documentation index, see https://buildwithfern.com/learn/llms.txt. ## 0.57.16 **`(fix):`** Fix an issue where environment URLs would be incorrectly remapped during the merge IR step. ## 0.57.15 **`(fix):`** Add support for handling nullable and optional references in the OpenAPI parser. When a reference is marked with `nullable: true` or is not included in the required properties list, the parser now correctly wraps the referenced type in a nullable or optional container. This ensures that references respect the same nullability and optionality rules as inline schemas.