apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/environment/DefaultPortalMetaServerProvider.java/DefaultPortalMetaServerProvider/getDomainsFromOSEnvironment
class DefaultPortalMetaServerProvider:    private Map<Env, String> getDomainsFromOSEnvironment() {
        // find key-value from OS environment variable which key ends with "_meta" (case insensitive)
        Map<String, String> metaServerAddressesFromOSEnvironment = KeyValueUtils.filterWithKeyIgnoreCaseEndsWith(System.getenv(), "_meta");
        // remove key's suffix "_meta" (case insensitive)
        metaServerAddressesFromOSEnvironment = KeyValueUtils.removeKeySuffix(metaServerAddressesFromOSEnvironment, "_meta".length());
        return transformToEnvMap(metaServerAddressesFromOSEnvironment);
    }