BackpressureConverter retains backpressure when FED is masked

[Phil2812]

The backpressure converter caches the result of the last calculation [1], leading to FEDs that are masked having constant backpressure in the produced snapshots [2], as their time delta appears to remain zero (due to the flashlist not being updated). What is the reasoning behind retaining and returning the previous result?

[1]

DAQAggregator/src/main/java/rcms/utilities/daqaggregator/data/helper/BackpressureConverter.java

Line 60 in d79714c

return lastResult;

[2] cmsdaq/daqview-react#33

[hsakulin]

DAQView also shows back-pressure after a run has been stopped and the DAQ has been drained. There should be no such caching in the DAQ Aggregator.