added missng log trace

modules/samples/connectedcup/component/api/src/main/java/org/coffeeking/api/ConnectedCupServiceImpl.java

@@ -97,10 +97,10 @@ public class ConnectedCupServiceImpl implements ConnectedCupService {
             return Response.ok().entity(sensorDatas).build();
         } catch (AnalyticsException e) {
             String errorMsg = "Error on retrieving stats on table " + sensorTableName + " with query " + query;
-            log.error(errorMsg);
+            log.error(errorMsg, e);
             return Response.status(Response.Status.INTERNAL_SERVER_ERROR.getStatusCode()).entity(errorMsg).build();
         } catch (DeviceAccessAuthorizationException e) {
-            log.error(e.getErrorMessage());
+            log.error(e.getErrorMessage(), e);
             return Response.status(Response.Status.INTERNAL_SERVER_ERROR.getStatusCode()).build();
         }
     }