A CommandHandlerInvoker holds a PartialFunction from DomainCommand to F[immutable.Seq[DomainEvent]].
A CommandHandlerInvoker which F type member is defined as Future
A CommandHandlerInvoker which F type member is defined as Identity
A CommandHandlerInvoker which F type member is defined as Try
A CommandHandlerInvoker holds a PartialFunction from DomainCommand to F[immutable.Seq[DomainEvent]]. F being the higher-kind wrapping the result of handling the command.