public static ConfigSourceSet createDefault() {
        String configSources = System.getenv("VESPA_CONFIG_SOURCES");
        if (configSources != null) {
            log.log(INFO, "Using config sources from VESPA_CONFIG_SOURCES: " + configSources);
            return new ConfigSourceSet(checkSourcesSyntax(configSources));
        } else {
            String[] def = {"tcp/localhost:" + System.getProperty("vespa.config.port", "19090")};
            String[] sourceSet = checkSourcesSyntax(System.getProperty("configsources"));
            return new ConfigSourceSet(sourceSet == null ? def : sourceSet);
        }
    }
Create a new source set using the environment variables or system properties
@return a new source set if available, null if not.
config/src/main/java/com/yahoo/config/subscription/ConfigSourceSet.java