In our project, we did use 'extra' in seriesDefault to store our own value and this value can be retrieved in 'valueFormatterFunction'. Then, we try to store another value into 'extra' in series array. We found that we failed to retrieve the value that we stored at seriesDefault.extra when valueFormatterFunction is called (Only the value in series[n].extra can be retrieved).
Does this mean the value that we assigned to seriesDefault would not take effect when the same variable exists in series[n]?