Il faut prendre un GeoJSON en entrée du type Feature comme ci-dessous
{"type":"FeatureCollection","features":[{"type":"Feature","properties":{},"geometry":{"coordinates":[[[-1.5567700133586584,47.21868047390478],[-1.5567362349704865,47.21787748555562],[-1.5560156293505258,47.21776277194195],[-1.5554413967479377,47.21783924771219],[-1.5554301372852422,47.21858870442267],[-1.5558917752596528,47.218802832966105],[-1.5560494077386977,47.21878753809898],[-1.556398451085954,47.21872635858563],[-1.5567700133586584,47.21868047390478]]],"type":"Polygon"}}]}
Ensuite, il faut prendre le bloc après "geometry":