fix concurrency issue in Statistics

src/main/java/net/floodlightcontroller/statistics/web/BandwidthResource.java

@@ -70,7 +70,7 @@ public class BandwidthResource extends ServerResource {
                 //fix concurrency scenario
                 IOFSwitch sw = switchService.getSwitch(dpid);
                 if (sw == null){
-                		return Collections.singletonMap("ERROR", "Switch was not online: " + dpid);
+                	return Collections.singletonMap("ERROR", "Switch was not online: " + dpid);
                 }
                 for (OFPortDesc pd : sw.getPorts()) { /* do specific DPID; do all ports */
                     SwitchPortBandwidth spb = statisticsService.getBandwidthConsumption(dpid, pd.getPortNo());