Here is a quick module to show how to customize your Developer Portal to enable OAuth flow for client_credentials and password grant flows when using SmartDocs.
https://github.com/giteshk/smartdocs_oauth_additions
Please use this as an example to write your own module for this functionality.
Article on how to import a new module in Drupal here
Updates to this module are only supported by reporting issues on GitHub or by creating pull requests.