private void addRule(OutlierRule newRule) {
        if (rules == null) {
            rules = newRule;
        } else {
            rules = rules.orElse(newRule);
        }
    }
Reports the specified {@link OutlierDetectionDecision} if the exception type is raised.
core/src/main/java/com/linecorp/armeria/common/outlier/OutlierDetectingRuleBuilder.java