code: function handleResponse() {
  		if (this.readyState === 4 && this.pendingInteraction && !this.pendingInteraction.completed) {
  			// enrich interaction with information
  			var sContentLength = this.getResponseHeader("content-length"),
  				bCompressed = this.getResponseHeader("content-encoding") === "gzip",
  				sFesrec = this.getResponseHeader("sap-perf-fesrec");
  			this.pendingInteraction.bytesReceived += sContentLength ? parseInt(sContentLength) : 0;
  			this.pendingInteraction.bytesReceived += this.getAllResponseHeaders().length;
  			this.pendingInteraction.bytesSent += this.requestHeaderLength || 0;
  			// this should be true only if all responses are compressed
  			this.pendingInteraction.requestCompression = bCompressed && (this.pendingInteraction.requestCompression !== false);
  			// sap-perf-fesrec header contains milliseconds
  			this.pendingInteraction.networkTime += sFesrec ? Math.round(parseFloat(sFesrec, 10) / 1000) : 0;
  			var sSapStatistics = this.getResponseHeader("sap-statistics");
  			if (sSapStatistics) {
  				var aTimings = window.performance.getEntriesByType("resource");
  				this.pendingInteraction.sapStatistics.push({
  					// add response url for mapping purposes
  					url: this.responseURL,
  					statistics: sSapStatistics,
  					timing: aTimings ? aTimings[aTimings.length - 1] : undefined
  				});
  			}
  			delete this.requestHeaderLength;
  			delete this.pendingInteraction;
  		}
  	}
docs: response handler which uses the custom properties we added to the xhr to retrieve information from the response headers