presto-main/src/main/java/io/prestosql/server/SessionPropertyDefaults.java/SessionPropertyDefaults/loadConfigurationManager
class SessionPropertyDefaults:    public void loadConfigurationManager()
            throws IOException
    {
        File configFile = CONFIG_FILE.getAbsoluteFile();
        if (!configFile.exists()) {
            return;
        }

        Map<String, String> properties = new HashMap<>(loadProperties(configFile));

        String name = properties.remove(NAME_PROPERTY);
        checkState(!isNullOrEmpty(name), "Session property configuration %s does not contain '%s'", configFile, NAME_PROPERTY);

        setConfigurationManager(name, properties);
    }