public CircuitBreakerMapping build(CircuitBreakerFactory factory) {
        if (!validateMappingKeys()) {
            throw new IllegalStateException("A CircuitBreakerMapping must be per host, method and/or path");
        }
        return new KeyedCircuitBreakerMapping(isPerHost(), isPerMethod(), isPerPath(), factory);
    }
Returns a newly-created {@link CircuitBreakerMapping} with the specified {@link CircuitBreakerFactory}
and properties set so far.
core/src/main/java/com/linecorp/armeria/client/circuitbreaker/CircuitBreakerMappingBuilder.java