@SuppressWarnings("unchecked")
	private static Map<String, Object> getOrAdd(MutablePropertySources sources, String name) {
		if (sources.contains(name)) {
			return (Map<String, Object>) sources.get(name).getSource();
		}
		Map<String, Object> map = new HashMap<>();
		sources.addFirst(new SystemEnvironmentPropertySource(name, map));
		return map;
	}
@author Spencer Gibb
@author Matt Jenkins
@author Olga Maciaszek-Sharma
@author Tim Ysewyn
spring-cloud-netflix-eureka-client/src/test/java/org/springframework/cloud/netflix/eureka/EurekaClientAutoConfigurationTests.java