One query handler and the query type the bus routes to it.
readonly
type: string
Query type name, matching query.type.
readonly
handler: IQueryHandler | RegistryFactory<IQueryHandler>
The handler to register for that type, or a factory that builds one from the service registry.
See CommandHandlerRegistration.handler for the instance and
factory arms and their timing.
CommandHandlerRegistrationfor why the handler is typed at the interface's defaults.