Deegree: how to cope with GML with an Arc: "Cannot determine control points for ring, contains non-linear segments"?

Question

How can I read with 'deegree' a GML3.2 with an arc?

The simplified data contains an arc:

<gml:Polygon>
  <gml:exterior>
    <gml:Ring>
      <gml:curveMember>
        <gml:Curve>
          <gml:segments>
            <gml:LineStringSegment>
              <gml:posList>44.605 773.516 40.806 775.320</gml:posList>
            </gml:LineStringSegment>
            <gml:LineStringSegment>
              <gml:posList>40.806 775.320 38.522 759.491</gml:posList>
            </gml:LineStringSegment>
            <gml:LineStringSegment>
              <gml:posList>38.522 759.491 45.178 773.702</gml:posList>
            </gml:LineStringSegment>
            <gml:Arc>
              <gml:posList>45.178 773.702 44.930 773.491 44.605 773.516</gml:posList>
            </gml:Arc>
          </gml:segments>
        </gml:Curve>
      </gml:curveMember>
    </gml:Ring>
  </gml:exterior>
</gml:Polygon>

When performing this method

GMLObject gmlObject = null;
XMLStreamReader r = XMLInputFactory.newInstance().createXMLStreamReader(new StringReader(gml));
GMLStreamReader gmlStreamReader = GMLInputFactory.createGMLStreamReader(gmlVersion, r);
gmlObject = gmlStreamReader.read(); // --> error 1
gmlObject.toString(); // --> error 2

I get these errors:

1. Method threw 'java.lang.IllegalArgumentException' exception. Cannot evaluate org.deegree.geometry.standard.primitive.DefaultPolygon.toString()
2. java.lang.IllegalArgumentException: Cannot determine control points for ring, contains non-linear segments.

How to cope with this issue?

Answer 1

EDIT

[The GML is not valid] -> I suppose that deegree thinks that the GML is not valid, because the upper level element is <gml:Polygon>, and by some definitions polygons can contain only straight segments. Maybe therefore <gml:Arc> that appears deeper in the data gives an error.

Arc and other curved element are allowed in a PolygonPatch https://datypic.com/sc/niem21/e-gml32_PolygonPatch.html.