Receive one message from the test actor and assert that it is of the specified type. Wait time is bounded by the given duration, if specified; otherwise wait time is bounded by remaining time for execution of the innermost enclosing 'within' block, if inside a 'within' block; otherwise by the config value "akka.test.single-expect-default".

public T ExpectMsg<T>(
	Nullable<TimeSpan> duration = null,
	string hint = null
)

member ExpectMsg : 
        ?duration : Nullable<TimeSpan> * 
        ?hint : string 
(* Defaults:
        let _duration = defaultArg duration null
        let _hint = defaultArg hint null
*)
-> 'T