Grouping does not work on TimeSeriesPlot for DateTimeColumn

[Sparkwired]

The following will not work when the timestamp column is a DateTimeColumn instead of a DateColumn:

Figure timeseries = TimeSeriesPlot.create("Ask price", t, "timestamp", "ask_price", "series");

java.lang.ClassCastException: tech.tablesaw.api.DateTimeColumn cannot be cast to tech.tablesaw.api.DateColumn
at tech.tablesaw.table.Relation.dateColumn(Relation.java:444)
at tech.tablesaw.plotly.api.TimeSeriesPlot.create(TimeSeriesPlot.java:27)

[Sparkwired]

This is a quick and dirty fix:

public static Figure create(
String title, Table table, String dateColX, String yCol, String groupCol) {

	    TableSliceGroup tables = table.splitOn(table.categoricalColumn(groupCol));

	    Layout layout = Layout.builder(title, dateColX, yCol).build();

	    ScatterTrace[] traces = new ScatterTrace[tables.size()];
	    for (int i = 0; i < tables.size(); i++) {
	      List<Table> tableList = tables.asTableList();
	      Table t = tableList.get(i).sortOn(dateColX);
	      
	      if (ColumnType.LOCAL_DATE.equals(table.column(dateColX).type())) {
	    	  traces[i] =
			          ScatterTrace.builder(t.dateColumn(dateColX), t.numberColumn(yCol))
			              .showLegend(true)
			              .name(tableList.get(i).name())
			              .mode(ScatterTrace.Mode.LINE)
			              .build();
	      } else if (ColumnType.LOCAL_DATE_TIME.equals(table.column(dateColX).type())) {
	    	  traces[i] =
			          ScatterTrace.builder(t.dateTimeColumn(dateColX), t.numberColumn(yCol))
			              .showLegend(true)
			              .name(tableList.get(i).name())
			              .mode(ScatterTrace.Mode.LINE)
			              .build();
	      }
	      
	      
	    }
	    return new Figure(layout, traces);
	  }