@Override
  public QuotaSource getQuotaSource() {
    try {
      return new TestCUQuotaSource(quotaConfig, accountService, quotaMetrics, routerConfig);
    } catch (IOException ioException) {
      return null;
    }
  }
Constructor for {@link AmbryCUQuotaSourceFactory}.
@param quotaConfig {@link QuotaConfig} object.
@param accountService {@link AccountService} object.
@param quotaMetrics {@link QuotaMetrics} object.
@param routerConfig {@link RouterConfig} object.
ambry-router/src/test/java/com/github/ambry/router/TestCUQuotaSourceFactory.java