log a warning for a legacy condition

webservice/webservice.py

@@ -405,6 +405,10 @@ def decide_run_parameters(runs, expected_number_of_runs):
     """
 
     if expected_number_of_runs == 3 and len(runs) == 1:
+        # log a warning to check if this legacy condition have ever been used.
+        logging.warning(
+            "A detector with 3 run numbers operation mode,"
+            f" but one dark run is requested. runs: {runs}")
         return {'run-high': runs[0], 'run-med': '0', 'run-low': '0'}
     elif expected_number_of_runs == 3 and len(runs) == 3:
         return {'run-high': runs[0], 'run-med': runs[1], 'run-low': runs[2]}