ADDITIONAL SYSTEM INFORMATION :
macos Catalina, Retina iMac (HiDPI)
JavaFX 15.0.1, Java 15.0.1


A DESCRIPTION OF THE PROBLEM :
The series stroke in a LineChart, when it is at the min or max value on the y axis, is clipped and not shown at full width.

I have a test program and some output images.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the attached program.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The series stroke should always be full width, even at min and max y.
ACTUAL -
The series stroke should always be full width.

---------- BEGIN SOURCE ----------
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.chart.LineChart;
import javafx.scene.chart.NumberAxis;
import javafx.stage.Stage;

public class LineChartClipping extends Application {

  LineChart.Series<Number, Number> series;

  LineChart<Number, Number> makeChart() {
    NumberAxis xAxis = new NumberAxis();
    NumberAxis yAxis = new NumberAxis(0, 1, .1); // -0.05, 1.05, .1);
    var chart = new LineChart<>(xAxis, yAxis) {
      @Override // Remove output clutter. Has no effect on the issue.
      protected void dataItemAdded(Series<Number, Number> series, int i, Data<Number, Number> item) {}
    };
    xAxis.setLowerBound(0);
    chart.setHorizontalGridLinesVisible(true);
    // Remove output clutter. Has no effect on the issue.
    chart.setLegendVisible(false);
    xAxis.setTickLabelsVisible (false);
    xAxis.setTickMarkVisible (false);
    xAxis.setMinorTickVisible (false);
    chart.setVerticalGridLinesVisible(false);
    yAxis.setTickLabelsVisible (false);
    yAxis.setTickMarkVisible (false); // true
    series = new LineChart.Series<>();
    chart.getData().add(series);
    series.getNode().setStyle(String.format("-fx-stroke-width: %g;", 3.0));
    addSegments(0.5, 0.0, 1.0, 0.5, 0.1, 0.9, 0.5);
    // Ineffectual tweaks
 // chart.setBackground(new Background(new BackgroundFill(Color.color(0, 1, 1, .5), null, null)));
 // chart.setPadding(new Insets(5, 0, 5, 0)); // also tried negative
    return chart;
  }

  double x = 0;

  void addSegments(double... values) {
    for (var value : values) {
      addData(value); x += 2;
      addData(value);
    }
  }

  private void addData(double value) {
    series.getData().add(new LineChart.Data<>(x, value));
  }


  @Override
  public void start(Stage stage) {
    var chart = makeChart();
    final Scene scene = new Scene(chart, 100, 100);
    stage.setScene(scene);
    stage.show();
  }

  public static void main(String[] args) { launch(args); }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
two possible workarounds have other problems. See screen shots. (Assuming I can attach them later.)

FREQUENCY : always