@Bean
		@ConditionalOnMissingBean(CircuitBreakerNameResolver.class)
		public CircuitBreakerNameResolver feignClientCircuitNameResolver(
				ObjectProvider<List<AbstractCircuitBreakerFactory>> provider) {
			List<AbstractCircuitBreakerFactory> factories = provider
					.getIfAvailable(Collections::emptyList);
			if (factories.size() >= 1) {
				return new FeignClientCircuitNameResolver(factories.get(0));
			}
			throw new IllegalArgumentException(
					"need one CircuitBreakerFactory/ReactiveCircuitBreakerFactory, but 0 found.");
		}
Auto configuration for feign client circuit breaker rules.

@author freeman
@since 2021.0.1.0
spring-cloud-alibaba-starters/spring-cloud-circuitbreaker-sentinel/src/main/java/com/alibaba/cloud/circuitbreaker/sentinel/feign/SentinelFeignClientAutoConfiguration.java