StringSelection cannot be deserialized

Cannot create property=fieldSelection for JavaBean=
StatisticsParameter (eva2.optimization.statistics.StatisticsParameters@4bae6387):
multiRuns=1, textOutput=0, verbosity= K-th iterations
To Text-window, [ currentBest meanFit currentWorst runBest currentBestFeasible runBestFeasible avgEucPopDistance maxEucPopDistance avgPopMetricDist maxPopMetricDist ]
 in 'reader', line 1, column 1:
    !!eva2.optimization.statistics.S ... 
    ^
java.lang.NoSuchMethodException: eva2.tools.StringSelection.<init>()
 in 'reader', line 3, column 17:
    fieldSelection: {}
                    ^

This prevents Statistics.yml and possibly other things from being saved/loaded.