@Override
    public void write(JmeExporter ex) throws IOException {
        super.write(ex);
        OutputCapsule out = ex.getCapsule(this);

        out.write(start, "startVertex", null);
        out.write(end, "endVertex", null);
    }
Alter the start and end.

@param start the desired mesh location of the start (not null,
unaffected)
@param end the desired mesh location of the end (not null, unaffected)
jme3-core/src/main/java/com/jme3/scene/shape/Line.java