private void overrideFromEnv() {
		if (environment == null) {
			return;
		}

		String prefix = NacosPropertiesPrefixer.getPrefix(environment);

		if (StringUtils.isEmpty(this.getServerAddr())) {
			String serverAddr = environment
					.resolvePlaceholders("${" + prefix + ".config.server-addr:}");
			if (StringUtils.isEmpty(serverAddr)) {
				serverAddr = environment.resolvePlaceholders(
						"${" + prefix + ".server-addr:127.0.0.1:8848}");
			}
			this.setServerAddr(serverAddr);
		}
		if (StringUtils.isEmpty(this.getUsername())) {
			this.setUsername(
					environment.resolvePlaceholders("${" + prefix + ".username:}"));
		}
		if (StringUtils.isEmpty(this.getPassword())) {
			this.setPassword(
					environment.resolvePlaceholders("${" + prefix + ".password:}"));
		}
	}
the master switch for refresh configuration, it default opened(true).
spring-cloud-alibaba-starters/spring-alibaba-nacos-config/src/main/java/com/alibaba/cloud/nacos/NacosConfigProperties.java