static Resilience4jCircuitBreakerMapping of() {
        return KeyedResilience4jCircuitBreakerMapping.MAPPING;
    }
Returns the default {@link Resilience4jCircuitBreakerMapping}.
A {@link CircuitBreaker} will be created per host using a {@link CircuitBreakerRegistry}
with default configurations.
resilience4j2/src/main/java/com/linecorp/armeria/resilience4j/circuitbreaker/client/Resilience4jCircuitBreakerMapping.java