code: public static void toGeojsonMultiPoint(MultiPoint multiPoint, StringBuilder sb) {
          sb.append("{\"type\":\"MultiPoint\",\"coordinates\":");
          toGeojsonCoordinates(multiPoint.getCoordinates(), sb);
          sb.append("}");
      }
docs: Coordinates of a MultiPoint are an array of positions.
  
  Syntax:
  
  { "type": "MultiPoint", "coordinates": [ [100.0, 0.0], [101.0, 1.0] ] }
  
  @param multiPoint
  @param sb