code: @Override
      public Shape toSpatial4j(SpatialContext spatialContext) {
          double kms = distance.getValue(GeoDistanceUnit.KILOMETRES);
          double d = DistanceUtils.dist2Degrees(kms, DistanceUtils.EARTH_MEAN_RADIUS_KM);
          return spatialContext.makeCircle(longitude, latitude, d);
      }
docs: {@inheritDoc}