examples/problematic_structure/problematic_nested_geometrycollection.geojson

{ "type": "GeometryCollection",
  "geometries": [
    { "type": "Point",
      "coordinates": [101.0, 2.0]
      },
    { "type": "GeometryCollection",
      "geometries": [
        { "type": "Point",
          "coordinates": [100.0, 0.0]
          },
        { "type": "LineString",
          "coordinates": [ [101.0, 0.0], [102.0, 1.0] ]
          }
       ]
      }
  ]
}