The Genesys Cloud CX Platform API adheres to RESTful principles for resource manipulation. To update an existing user, the PATCH HTTP method is used. This method is specifically designed to apply partial modifications to a resource. For instance, changing a user's name or phone number without affecting their other attributes. The designated API endpoint for this operation is PATCH /api/v2/users/{userId}, where {userId} is the unique identifier for the user being updated.

A. POST: This method is used for creating a new resource, such as adding a new user to the system, not for modifying an existing one.

C. TRACE: This is a diagnostic method used for network path debugging and does not perform any data manipulation on the resource.

D. DELETE: This method is used to permanently remove a resource, which is the opposite of updating a user's information.

1. Genesys Cloud Developer Center, Platform API v2, Users: The official API documentation explicitly lists the endpoint for updating a user.

Reference: PATCH /api/v2/users/{userId}

Description: "Update a user"

Source: Genesys Cloud CX, Developer Center, API Explorer, Users > patch-api-v2-users--userId-. (developer.genesys.cloud/api/rest/v2/users/#patch-api-v2-users--userId-)