code: protected void writeCrs(JsonGenerator jgen, Geometry shape)
              throws IOException {
          /*
              "crs": {
              "type": "name",
              "properties": {
                  "name": "EPSG:xxxx"
                  }
              }
          */
          if (shape.getSRID() > 0) {
              jgen.writeFieldName("crs");
              jgen.writeStartObject();
              jgen.writeStringField("type", "name");
              jgen.writeFieldName("properties");
              jgen.writeStartObject();
              jgen.writeStringField("name", "EPSG:" + shape.getSRID());
              jgen.writeEndObject();
              jgen.writeEndObject();
          }
      }
docs: Writes out the crs information in the GeoJSON string
  
  @param jgen  the jsongenerator used for the geojson construction
  @param shape the geometry for which the contents is to be retrieved
  @throws java.io.IOException If the underlying jsongenerator fails writing the contents