Cannot successfully add item to beginning of CategoryAxis series for a JavaFX BarChart - mouseevent

Question

I've attempted to implement drag-left and drag-right functionality for a JavaFX BarChart. The drag-left functionality works correct where I add an item at the end of the x-axis data series and remove an item at the beginning.
However, the drag-right functionality does not work as expected. It's supposed to add an item at the beginning of the x-axis series and remove an item at the end. The removal works correctly, but the add operation results in the item being added to the end of the BarChart instead of the beginning.
I suspect it has to do with the use of a CategoryAxis that does not recognize the need to update the BarChart from the ObservableList in a sorted manner (even though I can see that the item gets added to the beginning of the underlying ObservableList).
Also, please let me know if there is a better way of implementing the drag operation.
Below is a full application to reproduce the problem.
import java.text.SimpleDateFormat;
import java.util.Date;
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.scene.Scene;
import javafx.scene.chart.BarChart;
import javafx.scene.chart.CategoryAxis;
import javafx.scene.chart.NumberAxis;
import javafx.scene.chart.XYChart;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
public class BarchartProblem extends Application {
private static SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");
private double dragStartX = 0;
private long minTime;
private long maxTime;
#FXML
private BarChart<String,Number> histogramBarChart;
#Override
public void start(Stage primaryStage) {
final CategoryAxis xAxis = new CategoryAxis();
final NumberAxis yAxis = new NumberAxis();
xAxis.setLabel("Time");
yAxis.setLabel("Entries");
histogramBarChart = new BarChart<String, Number>(xAxis, yAxis);
final XYChart.Series series1 = new XYChart.Series();
histogramBarChart.setLegendVisible(false);
histogramBarChart.getData().addAll(series1);
histogramBarChart.setOnMousePressed(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent mouseEvent) {
System.out.println(mouseEvent);
dragStartX = mouseEvent.getX();
}
});
histogramBarChart.setOnMouseDragged(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent mouseEvent) {
if (dragStartX > mouseEvent.getX()) {
XYChart.Series series = histogramBarChart.getData().get(0);
minTime += 60000;
maxTime += 60000;
series.getData().add(new XYChart.Data(dateFormat.format(new Date(maxTime)), 0));
series.getData().remove(0);
System.out.println("Drag Left");
} else if (dragStartX < mouseEvent.getX()) {
XYChart.Series series = histogramBarChart.getData().get(0);
minTime -= 60000;
maxTime -= 60000;
series.getData().add(0, new XYChart.Data(dateFormat.format(new Date(minTime)), 0));
series.getData().remove(series.getData().size()-1);
System.out.println("Drag Right");
}
}
});
final long currentTime = System.currentTimeMillis();
minTime = currentTime-60000*30;
maxTime = currentTime;
for (long i = minTime; i <= maxTime; i += 60000) {
series1.getData().add(new XYChart.Data(dateFormat.format(new Date(i)), Math.random()*500));
}
StackPane root = new StackPane();
root.getChildren().add(histogramBarChart);
Scene scene = new Scene(root, 300, 250);
primaryStage.setTitle("BarChart Problem");
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}