public DeadLettersFilter(
	IStringMatcher messageMatcher,
	IStringMatcher sourceMatcher,
	Predicate<DeadLetter> isMatch = null
)

new : 
        messageMatcher : IStringMatcher * 
        sourceMatcher : IStringMatcher * 
        ?isMatch : Predicate<DeadLetter> 
(* Defaults:
        let _isMatch = defaultArg isMatch null
*)
-> DeadLettersFilter