v9.4.0-snapshot

Modify/set the headers in sendErrorCallback only in case it is explicitly requested to do so, as this function is called in two cases:
// 1. (do not modify them) when the Switch needs to relay an error, e.g. from a DFSP to another
// 2. (modify/set them) when the Switch needs to send errors that are originating in the Switch, e.g. to send an error back to the caller