The GitLab API for adding a SAML group link supports an optional `provider` attribute to specify a unique provider name that must match for the group link to be applied. This property is currently missing from the `AddGroupSAMLLinkOptions` struct. **Reference:** GitLab API documentation: https://docs.gitlab.com/api/saml/#add-a-saml-group-link **Proposed Solution:** * Add `Provider *string` to `AddGroupSAMLLinkOptions`. * Add `Provider string` to the base `SAMLGroupLink` struct. * Implement a unit test (`TestAddGroupSAMLLinkWithProvider`) to verify the behavior.