code: public static String toJsonString(Object val, boolean pretty) {
          try {
              return pretty ? mapper.writerWithDefaultPrettyPrinter().with(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS).writeValueAsString(val) : mapper.writeValueAsString(val);
          } catch (Exception e) {
              throw new RuntimeException(e);
          }
      }
docs: Convert Java object to a JSON string.
  
  @param val Java object
  @param pretty enable/disable pretty print
  @return JSON string.