BUG: handle cases where there is only one DopplerCentroid, AzimuthFMRate or...

BUG: handle cases where there is only one DopplerCentroid, AzimuthFMRate or Orbit available (happens on WV products)
18 jobs for !864 with sar_io_2 in 104 minutes and 34 seconds (queued for 4 seconds)
merge request