trying to port painting game to phaser 3 and lineCap is missing from graphics

[Taribuna]

Hello,
I am trying to port a coloring book "game" from phaser 2 to phaser 3. 
Now in the original we used to do a simpe draw with the mouse using:
 

var canvas = this.make.bitmapData(800, 600);
var ctx = canvas.ctx;
ctx.lineWidth = 20;
ctx.lineJoin = ctx.lineCap = 'round';
ctx.strokeStyle = '#000000';

// and then in the mouse move function


ctx.beginPath();	
ctx.moveTo(last_pos.x, last_pos.y);
ctx.lineTo(pointer.x, pointer.y);
ctx.stroke();
ctx.closePath();

Now in the new Graphics Class I did not find a way to set the lineCap to round. 
Hence when I run:
 

var canvas = this.add.graphics();
canvas.lineStyle(20, 0x000000, 1);
canvas.beginPath();
canvas.moveTo(drawpoint.x, drawpoint.y);
canvas.lineTo(pointer.x,pointer.y);
canvas.fillPath()
canvas.strokePath();
canvas.closePath();

i am not getting a nice smooth line but rather the very jagged path that I would get if I did not set lineCap to "round" in the old version. 

Any Ideas what I could do?
thanks!