Fix circuit breaker Feign builder direct usage

[hutiefang76]

Fixes gh-1210.

When the circuit breaker Feign.Builder bean is used directly, it currently gets created without the CircuitBreakerFactory, group setting, or CircuitBreakerNameResolver that the normal Feign client targeter path applies later. That makes the direct builder path fail at invocation time instead of behaving like the regular circuit breaker Feign client path.

This change configures the circuit breaker builder bean with the available factory, group flag, and resolver. It also falls back to the Feign target name when the builder is used outside the named Feign client targeter path.

Tests added for:

• direct Feign.Builder bean configuration with circuit breaker enabled
• fallback resolver behavior when no resolver bean is available
• using the target name when feignClientName is not set

Tested with:

./mvnw -pl spring-cloud-openfeign-core -Dtest=FeignAutoConfigurationTests test

[Copilot]

Pull request overview

This pull request fixes gh-1210 by ensuring the circuit breaker Feign.Builder bean is fully configured (factory, group flag, and name resolver) when it is used directly, so it behaves consistently with the normal Feign client targeter path. It also makes circuit breaker name/group resolution work when the builder is used outside the named Feign client path by falling back to the Feign Target name.

Changes:

• Configure the circuit-breaker Feign.Builder bean with CircuitBreakerFactory, group-enabled flag, and a resolver fallback when no CircuitBreakerNameResolver bean is present.
• Update FeignCircuitBreakerInvocationHandler to use target.name() when feignClientName is not set (for direct builder usage).
• Add tests covering direct builder configuration and target-name fallback behavior.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
spring-cloud-openfeign-core/src/test/java/org/springframework/cloud/openfeign/FeignAutoConfigurationTests.java	Adds tests for direct circuit breaker builder configuration and target-name fallback behavior.
spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignClientsConfiguration.java	Configures the circuit breaker Feign.Builder bean with factory/group/resolver (including a default resolver fallback).
spring-cloud-openfeign-core/src/main/java/org/springframework/cloud/openfeign/FeignCircuitBreakerInvocationHandler.java	Falls back to target.name() when feignClientName is null for circuit/group naming.

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[ryanjbaxter]

Technically I believe the fallback name resolver would be AlphanumericCircuitBreakerNameResolver by default if alphanumeric-ids.enabled has matchIfMissing = true. We should probably check that property and use the correct name resolver