For the template method, there are seven types of participant resolvers:
Participants are members of roles that grant access to the approval task.
Participants are a specified list of users.
Participants are members of a specified list of groups.
Participants are members of a specified list of admin roles.
Participants are members of admin roles associated with a specified list of admin tasks.
Participants are dynamically selected depending on the task or event being approved.
This resolves to a null list with no users.
Participants are determined by a custom participant resolver.