code: func (client *Client) UpdateOrganizationManagerByUsername(guid string, username string) (Warnings, error) {
  	requestBody := updateOrgManagerByUsernameRequestBody{
  		Username: username,
  	}
  
  	body, err := json.Marshal(requestBody)
  	if err != nil {
  		return nil, err
  	}
  
  	request, err := client.newHTTPRequest(requestOptions{
  		RequestName: internal.PutOrganizationManagerByUsernameRequest,
  		Body:        bytes.NewReader(body),
  		URIParams:   Params{"organization_guid": guid},
  	})
  	if err != nil {
  		return nil, err
  	}
  
  	response := cloudcontroller.Response{}
  	err = client.connection.Make(request, &response)
  
  	return response.Warnings, err
  }
docs: // UpdateOrganizationManagerByUsername assigns the org manager role to the user with the provided name.