Duplicate points on edges

[tylerlong]

Describe the bug
There are duplicate points on edges. It makes the SVG marker-end arrow head have a wrong direction.

Reproduce it

You can see that the arrow head on top is facing left, but it is supposed to face down. Root cause is there are two duplicate points on the edge, which makes SVG cannot decide the direction, so it use the default direction.

Expected behavior
There shouldn't be duplicate points on an edge.

ELK Version
0.9.3

Additional context

"startPoint": {
            "x": 194.4,
            "y": 210.39999999999998
          },
          "endPoint": {
            "x": 133.6,
            "y": 44
          },
          "bendPoints": [
            {
              "x": 194.4,
              "y": 210.39999999999998
            },
            {
              "x": 194.39999999999998,
              "y": 226.39999999999998
            },
            {
              "x": 163.99999999999994,
              "y": 234.39999999999995
            },
            {
              "x": 133.59999999999997,
              "y": 242.39999999999995
            },
            {
              "x": 72.80000000000001,
              "y": 242.39999999999995
            },
            {
              "x": 42.40000000000002,
              "y": 237.0666666666666
            },
            {
              "x": 12,
              "y": 231.7333333333333
            },
            {
              "x": 12,
              "y": 221.06666666666666
            },
            {
              "x": 12,
              "y": 201.86666666666662
            },
            {
              "x": 12,
              "y": 182.66666666666663
            },
            {
              "x": 12,
              "y": 154.9333333333333
            },
            {
              "x": 12,
              "y": 134.13333333333333
            },
            {
              "x": 12,
              "y": 113.33333333333331
            },
            {
              "x": 12,
              "y": 99.46666666666665
            },
            {
              "x": 12,
              "y": 85.59999999999998
            },
            {
              "x": 12,
              "y": 71.73333333333332
            },
            {
              "x": 12,
              "y": 57.86666666666666
            },
            {
              "x": 12,
              "y": 45.599999999999994
            },
            {
              "x": 12,
              "y": 33.33333333333333
            },
            {
              "x": 12,
              "y": 22.666666666666664
            },
            {
              "x": 32.266666666666666,
              "y": 17.333333333333332
            },
            {
              "x": 52.53333333333333,
              "y": 12
            },
            {
              "x": 93.06666666666666,
              "y": 12
            },
            {
              "x": 113.3333333333333,
              "y": 20
            },
            {
              "x": 133.59999999999997,
              "y": 28
            },
            {
              "x": 133.6,
              "y": 44
            }
          ],

You can see that startPoint === bendPoints[0] and endPoint === bendPoints[bendPoints.length-1].

But this doesn't happen to other edges, only this edge has the issue.

[soerendomroes]

This seems to be an issue with the SPLINES edge routing, correct?

[tylerlong]

This seems to be an issue with the SPLINES edge routing, correct?

Confirmed. SPLINES edge routing only issue.

[soerendomroes]

Thanks, we will investigate.