Message sent by user

Type of the source by which user is contacting. For example:
- phone - user is contacting by phone
- twitter - user message comes from twitter integration

Name of the author of the message.

Project identifier - uuid of a project for which bot has to respond

Session identifier. Session is unique identifier for one particular session. It can be an uuid or just random string.
If bot responds to user and integrator wants to send another message in the same context it has to attach the same suid
Example:
1. User sends first message in the conversation - set the suid for ex. "r123111-a99c-480c-89e1-e26b2f3f76b7"
2. Gateway returns message to user
3. User says something more in that particular conversation - use the same suid as before "r123111-a99c-480c-89e1-e26b2f3f76b7"