Defines a min user that was seen in a certain message of a certain chat.
inputUserFromMessage#1da448e2 peer:InputPeer msg_id:int user_id:long = InputUser;
|The chat where the user was seen
|The message ID
|The identifier of the user that was seen
In some situations user and channel constructors have reduced set of fields present (although id is always there) and min flag set.