code: public void setGeoCode(GeoLocation location, double radius
              , Unit unit) {
          this.geocode = location.getLatitude() + "," + location.getLongitude() + "," + radius + unit.name();
      }
docs: returns tweets by users located within a given radius of the given latitude/longitude, where the user's location is taken from their Twitter profile
  
  @param location geo location
  @param radius   radius
  @param unit     Query.MILES or Query.KILOMETERS
  @since Twitter4J 4.0.1