Cannot set 'via' fields when creating tickets using the API

I am trying to create tickets using the API but cannot seem to set the 'via' properties on ticket comments.

My use case is that I'm importing existing tickets from another product into Zendesk. These tickets were created automatically in response to an incoming email. So I think it makes sense to create a new ticket in Zendesk with the first comment containing the content of the email and having the 'via' properties on that comment contain the email info (e.g. from/to addresses & names)

The docs seem to suggest this is possible, but I am getting errors on ticket creation: `unpermitted_keys: ["ticket.comment.via.channel", "ticket.comment.via.source.to.address" ...]`

Example:

params = {:subject=>"test subject",
          :requester_id=>12345,
          :comment=> {
             :html_body=> "test email body",
             :author_id=>12345,
             :via=> {
                 :channel=>"email",
                 :source=> {
                     :to=> {
                        :address=>"support@mycompany.com"
                      },
                     :from=> {
                        :address=>"customer@gmail.com",  
                        :name=>"Customer name"}
                      }
             }, 
             :uploads=>[]},
             :status=>"closed"}
ZendeskAPI::Ticket.create!(client, params)

Any ideas on what I'm doing wrong?