private Boolean filterRule(final RuleData ruleData, final ServerWebExchange exchange) {
        return ruleData.getEnabled() && MatchStrategyFactory.match(ruleData.getMatchMode(), ruleData.getConditionDataList(), exchange);
    }
Handle rule if null mono.

@param pluginName the plugin name
@param exchange the exchange
@param chain the chain
@return the mono
shenyu-plugin/shenyu-plugin-base/src/main/java/org/apache/shenyu/plugin/base/AbstractShenyuPlugin.java