static void drawRoundEdgeLine(BufferedImage image, int x1, int y1, int x2, int y2, Color color, double width) {
  drawRoundEdgeLine(imageGraphics(image), x1, y1, x2, y2, color, width);
}

static void drawRoundEdgeLine(Graphics2D g, int x1, int y1, int x2, int y2, Color color, double width) {
  g.setColor(color);
  g.setStroke(new BasicStroke((float) width, BasicStroke.CAP_ROUND, BasicStroke.JOIN_MITER));
  g.drawLine(x1, y1, x2, y2);
}

static void drawRoundEdgeLine(BufferedImage image, Pt a, Pt b, Color color, double width) {
  drawRoundEdgeLine(imageGraphics(image), a, b, color, width);
}

static void drawRoundEdgeLine(Graphics2D g, Pt a, Pt b, Color color, double width) {
  drawRoundEdgeLine(g, a.x, a.y, b.x, b.y, color, width);
}

Began life as a copy of #1006921