The invitation object to check for available roles.
The template action being analyzed to determine which roles are expected.
Array of role identifier strings representing roles that can still accept participants. Returns an empty array if no roles are defined in the action.
Lists role identifiers for roles that still have capacity for additional participants. A role is considered available if the number of distinct entities that have filled it is less than the role's maximum slot count. If max is undefined, the role has unlimited capacity.