code: public GeospatialIndex geoJSONProperty(JSONProperty parent, JSONProperty jsonProperty) {
      if ( parent == null ) throw new IllegalArgumentException("parent cannot be null");
      if ( jsonProperty == null ) throw new IllegalArgumentException("jsonProperty cannot be null");
      return new GeoJSONPropertyImpl(parent, jsonProperty);
    }
docs: Identifies a parent json property with a child json property whose text has
  the latitude and longitude coordinates to match with a geospatial query.
  @param parent    the parent of the json property with the coordinates
  @param jsonProperty    the json property containing the geospatial coordinates
  @return    the specification for the index on the geospatial coordinates