public Resilience4jCircuitBreakerMappingBuilder factory(
            Resilience4jCircuitBreakerFactory factory) {
        this.factory = requireNonNull(factory, "factory");
        return this;
    }
A factory method which creates a {@link CircuitBreaker} instance based on the
specified {@link CircuitBreakerRegistry} and the mapping keys generated by the
{@link Resilience4jCircuitBreakerMapping}.
By default, each non-null mapping key is concatenated and used as the name for
{@link CircuitBreakerRegistry#circuitBreaker(String)}.

<pre>{@code
Resilience4jCircuitBreakerMapping
        .builder()
        .perHost()
        .factory((registry, host, method, path) -> registry.circuitBreaker(host, "configA"))
        .build();
}</pre>
resilience4j2/src/main/java/com/linecorp/armeria/resilience4j/circuitbreaker/client/Resilience4jCircuitBreakerMappingBuilder.java