CIDUnion

CorrelationID for commands and Sagas. A CID cannot contain '~'. FCQRS joins a CID to an aggregate ID with '~' to name sagas and pub-sub topics, and reads the CID back from the text after the last '~', so a CID containing one never reaches its saga. Creating such a CID throws ArgumentException; the constructor throws instead of returning an error so that FCQRS releases built against the previous signature keep working. Deserialization does not run this check, so IsValid reports it for a CID read from a message.