Union satisfied by.
type CustomChartsSectionChartsSingleCustomChartResponseSerializedSeriesGroupByDefinitionsUnion interfaceUnion satisfied by [CustomChartsSectionChartsSingleCustomChartResponseSerializedSeriesGroupByDefinitionsCustomChartGroupByPlain] or [CustomChartsSectionChartsSingleCustomChartResponseSerializedSeriesGroupByDefinitionsCustomChartGroupByComplex].