What is the JSON structure for an invitation, and under what circumstances is one returned. For example,
GET /1/boards/5144051cbd0da6681200201e/invitations?key=[myKey]
always returns an empty array, even after I invite a fake email.
That route no longer returns anything (and should probably be marked deprecated).
Instead of invitation objects, we add a member to the board representing the invited person (where member.memberType = "ghost") so that you can interact with that person (mention in comments, add to cards) before they join Trello. If you invited that person, you will be able to see the 'ghost' member's email address.