Lead
A lead is a set of answers against a questionnaire.
When a delegate interacts with a sponsor app, they are usually asked to answers to some questions, the app then posts these answers to the server as a lead so the sponsor can then follow up with those delegates.
Although this is usually related to a sponsor, a questionnaire can be set against any type of device, so this limitation is not enforced. Indeed a lead could also be:
a feedback against a particular session
a global feedback
a Q&A entry
some kind of rating
POST /lead/new
Saves a new lead.