apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/environment/DefaultPortalMetaServerProvider.java/DefaultPortalMetaServerProvider/getDomainsFromPropertiesFile
class DefaultPortalMetaServerProvider:    private Map<Env, String> getDomainsFromPropertiesFile() {
        // find key-value from properties file which key ends with ".meta" (case insensitive)
        Properties properties = new Properties();
        properties = ResourceUtils.readConfigFile(APOLLO_ENV_PROPERTIES_FILE_PATH, properties);
        Map<String, String> metaServerAddressesFromPropertiesFile = KeyValueUtils.filterWithKeyIgnoreCaseEndsWith(properties, ".meta");
        // remove key's suffix ".meta" (case insensitive)
        metaServerAddressesFromPropertiesFile = KeyValueUtils.removeKeySuffix(metaServerAddressesFromPropertiesFile, ".meta".length());
        return transformToEnvMap(metaServerAddressesFromPropertiesFile);
    }