Wavefront sink: filter out tags with blank values
Wavefront sink: filter out tags with blank values

whuwxl/heapster,bluebreezecf/heapster,whuwxl/heapster,krzyzacy/heapster,krzyzacy/heapster,Stackdriver/heapster,Stackdriver/heapster,bluebreezecf/heapster,piosz/heapster,piosz/heapster