Actor

{

  // Union field type can be only one of the following:
  "user": {
    object (User)
  },
  "anonymous": {
    object (AnonymousUser)
  },
  "impersonation": {
    object (Impersonation)
  },
  "system": {
    object (SystemEvent)
  },
  "administrator": {
    object (Administrator)
  }
  // End of list of possible types for union field type.
}

object (User)

An end user.

object (AnonymousUser)

An anonymous user.

object (Impersonation)

An account acting on behalf of another.

object (SystemEvent)

A non-user actor (i.e. system triggered).

object (Administrator)

An administrator.