code: func (e *quotaEvaluator) checkRequest(quotas []corev1.ResourceQuota, a admission.Attributes) ([]corev1.ResourceQuota, error) {
  	evaluator := e.registry.Get(a.GetResource().GroupResource())
  	if evaluator == nil {
  		return quotas, nil
  	}
  	return CheckRequest(quotas, a, evaluator, e.config.LimitedResources)
  }
docs: // checkRequest verifies that the request does not exceed any quota constraint. it returns a copy of quotas not yet persisted
  // that capture what the usage would be if the request succeeded.  It return an error if there is insufficient quota to satisfy the request