Use this endpoint to upload or update identity data for a client in an existing workflow.

For Document Authentication workflows, the following options are available:

• Use an existing client with a previously completed Identity Verification workflow. Fourthline reuses the existing client data.

• Upload previous client data directly. For this option, call this endpoint with a referenceDocumentData payload before uploading the new identity document.

Note: This endpoint is not required for Biometric Authentication workflows.

For error responses, inspect the response body for additional details:

• 400 Bad Request returns a validationProblemDetails object, including an errors property that maps request fields to validation error messages.
  
• All other error responses return a problemDetails object containing type, title, status, and detail.