code: public String toGeoJsonEnvelope(Envelope e) {
          return new StringBuffer().append("[").append(e.getMinX()).append(",")
                  .append(e.getMinY()).append(",").append(e.getMaxX()).append(",")
                  .append(e.getMaxY()).append("]").toString();
      }
docs: Convert a JTS Envelope to a GeoJSON representation.
  
  @param e The envelope
  
  @return The envelope encoded as GeoJSON