code: public static void toGeojsonCoordinates(Coordinate[] coords, StringBuilder sb) {
          sb.append("[");
          for (int i = 0; i < coords.length; i++) {
              toGeojsonCoordinate(coords[i], sb);
              if (i < coords.length - 1) {
                  sb.append(",");
              }
          }
          sb.append("]");
      }
docs: Convert a jts array of coordinates to a GeoJSON coordinates
  representation.
  
  Syntax:
  
  [[X1,Y1],[X2,Y2]]
  
  @param coords
  @param sb