private String prettyPrint(Object o) {
		try {
			return new ObjectMapper().enable(SerializationFeature.INDENT_OUTPUT)
					.writeValueAsString(o);
		}
		catch (JsonProcessingException e) {
			LOGGER.error("JSON serialization err.", e);
			return "__JSON format err__";
		}
	}
properties backup, prevent rules from being updated every time the container is
refreshed.
spring-cloud-alibaba-starters/spring-cloud-circuitbreaker-sentinel/src/main/java/com/alibaba/cloud/circuitbreaker/sentinel/feign/CircuitBreakerRuleChangeListener.java