Fixes:, return when nothing to collect. do not write if values is null.
Fixes:, return when nothing to collect. do not write if values is null.

pthivierge/web-service-reader-for-pi-system,pthivierge/data-collection-service-for-pi-system,pthivierge/web-service-reader-for-pi-system,pthivierge/data-collection-service-for-pi-system,pthivierge/data-collection-service-for-pi-system,pthivierge/web-service-reader-for-pi-system