To move a user from one population to another, you need to know the ID of the new population resource to associate with the user. To retrieve the list of all population IDs for a specified environment, you can call the GET /environments/{environmentId}/populations method.

The sample shows the PUT /environments/{environmentId}/users/{userId}/population operation to associate the user with the different population.

In the request body, the id attribute value is the population ID for the new population to associate with the user.