@Override
    public Config rewrite(String name, Config config) {
      ImmutableMap.Builder<String, String> newConfigMapBuilder = new ImmutableMap.Builder<>();
      newConfigMapBuilder.putAll(config);
      newConfigMapBuilder.put(NEW_CONFIG_KEY, config.get(CONFIG_KEY));
      return new MapConfig(newConfigMapBuilder.build());
    }
Adds a new config entry for the key {@link #NEW_CONFIG_KEY} which has the same value as {@link #CONFIG_KEY}.
samza-core/src/test/java/org/apache/samza/util/TestConfigUtil.java