shapes are not filled

[codeanticode]

The following code:

    fill(color(255, 0, 0));
    strokeWeight(7);
    strokeCap(PConstants.ROUND);
    beginShape();
    vertex(0, 0);
    vertex(100, 0);
    vertex(100, 100);
    vertex(50, 100);
    vertex(50, 150);
    vertex(20, 150);
    vertex(20, 100);
    vertex(0, 100);
    endShape(PConstants.CLOSE);

Results only in an outline, there is center red spine along the stroke, so it seems that the fill paint in the is interpreted in the way one would expect.