function fesrHeaderOverride() {

		// only use FESR for non CORS requests
		if (!isCORSRequest(arguments[1])) {

			if (sFESR && sFESRopt) {
				this.setRequestHeader("SAP-Perf-FESRec", sFESR);
				this.setRequestHeader("SAP-Perf-FESRec-opt", sFESRopt);
				sFESR = null;
				sFESRopt = null;
				sFESRTransactionId = Passport.getTransactionId();
			}
		}
	}
Sends the FESR header when using the piggyback aproach
@private