final CircuitBreakerRuleWithContent<O> ruleWithContent() {
        checkState(ruleWithContent != null, "ruleWithContent is not set.");
        return ruleWithContent;
    }
Creates a new builder with the specified {@link CircuitBreakerRuleWithContent}.
core/src/main/java/com/linecorp/armeria/client/circuitbreaker/AbstractCircuitBreakerClientBuilder.java