docs: @Override
  	public String toJson(Object obj) {
  		try {
  			String json;
  			if (obj == null) {
  				json = null;
  			}
  			else {
  				json = mapper.writeValueAsString(obj);
  			}
  			return json;
  		}
  		catch (Exception e) {
  			throw new JsonException(e.getMessage(), e);
  		}
  	}