public TestCUQuotaSource getTestCuQuotaSource() {
      for (QuotaEnforcer quotaEnforcer : quotaEnforcers) {
        if (quotaEnforcer instanceof AmbryCUQuotaEnforcer && !(quotaEnforcer instanceof RejectingQuotaEnforcer)) {
          return (TestCUQuotaSource) quotaEnforcer.getQuotaSource();
        }
      }
      throw new IllegalStateException("could not find TestCUQuotaSource in QuotaManager.");
    }
@return TestCUQuotaSource object from the {@link QuotaEnforcer}s.
ambry-router/src/test/java/com/github/ambry/router/NonBlockingQuotaTest.java