@Override
	public String[] getAvailabilityZones(String region) {
		String value = this.availabilityZones.get(region);
		if (value == null) {
			value = DEFAULT_ZONE;
		}
		return value.split(",");
	}
Order of the discovery client used by `CompositeDiscoveryClient` for sorting
available clients.
spring-cloud-netflix-eureka-client/src/main/java/org/springframework/cloud/netflix/eureka/EurekaClientConfigBean.java