code: public static void toGeojsonMultiLineString(MultiLineString multiLineString, StringBuilder sb) {
          sb.append("{\"type\":\"MultiLineString\",\"coordinates\":[");
          for (int i = 0; i < multiLineString.getNumGeometries(); i++) {
              toGeojsonCoordinates(multiLineString.getGeometryN(i).getCoordinates(), sb);
              if (i < multiLineString.getNumGeometries() - 1) {
                  sb.append(",");
              }
          }
          sb.append("]}");
      }
docs: Coordinates of a MultiLineString are an array of LineString coordinate
  arrays.
  
  Syntax:
  
  { "type": "MultiLineString", "coordinates": [ [ [100.0, 0.0], [101.0,
  1.0] ], [ [102.0, 2.0], [103.0, 3.0] ] ] }
  
  @param multiLineString
  @param sb