Vert.x circuit breaker bug

CBTest.java

package com.example.api.test;

import io.vertx.circuitbreaker.CircuitBreaker;
import io.vertx.circuitbreaker.CircuitBreakerOptions;
import io.vertx.core.Promise;
import io.vertx.core.Vertx;

public class CBTest {

    static Vertx vertx = Vertx.vertx();
    static CircuitBreaker breaker = CircuitBreaker.create("breakerName", vertx, new CircuitBreakerOptions()
            .setMaxRetries(0)
            .setTimeout(500)
            .setFallbackOnFailure(false)
            .setResetTimeout(500)
            .setMaxFailures(1))
        .closeHandler(CBTest::state)
        .openHandler(CBTest::state)
        .halfOpenHandler(CBTest::state);
    
    public static void main(String[] args) {
        vertx.getOrCreateContext()
            .exceptionHandler(ex -> ex.printStackTrace()) //intercept exceptions in the context
            .runOnContext(v -> {
                state(null);
                breaker.execute(CBTest::pingSuccess).onComplete(v1 -> {
                    breaker.execute(CBTest::pingDelay).onComplete(v2 -> {
                        System.out.println("wait for half-open...");
                        vertx.setTimer(1000, l -> {
                            breaker.execute(CBTest::pingSuccess).onComplete(v3 -> {
                                breaker.execute(CBTest::pingSuccess).onComplete(v4 -> {
                                   vertx.close();
                                });
                            });
                        });
                    });
                });
            });
    }

    public static void pingFail(Promise<Void> p) {
        System.out.println("fail");
        p.fail("ping fail");
    }

    public static void pingDelay(Promise<Void> p) {
        System.out.println("timeout");
        vertx.setTimer(500, l -> p.complete());
    }

    public static void pingSuccess(Promise<Void> p) {
        System.out.println("success");
        p.complete();
    }

    public static void state(Object o) {
        System.out.println(breaker.state());
    }
}

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--
  ~ Copyright (c) 2011-2016 The original author or authors
  ~
  ~ All rights reserved. This program and the accompanying materials
  ~ are made available under the terms of the Eclipse Public License v1.0
  ~ and Apache License v2.0 which accompanies this distribution.
  ~
  ~      The Eclipse Public License is available at
  ~      http://www.eclipse.org/legal/epl-v10.html
  ~
  ~      The Apache License v2.0 is available at
  ~      http://www.opensource.org/licenses/apache2.0.php
  ~
  ~ You may elect to redistribute this code under either of these licenses.
  --><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <parent>
    <groupId>io.vertx</groupId>
    <artifactId>vertx-ext-parent</artifactId>
    <version>34</version>
  </parent>

  <artifactId>vertx-circuit-breaker</artifactId>
  <version>4.0.0-SNAPSHOT</version>

  <properties>
    <hystrix.version>1.5.2</hystrix.version>
    <codegen.rxjava.deprecated>true</codegen.rxjava.deprecated>
  </properties>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>io.vertx</groupId>
        <artifactId>vertx-dependencies</artifactId>
        <version>${project.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>

  <dependencies>
    <dependency>
      <groupId>io.vertx</groupId>
      <artifactId>vertx-hazelcast</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>io.vertx</groupId>
      <artifactId>vertx-web</artifactId>
      <optional>true</optional>
    </dependency>
    <dependency>
      <!-- for metrics -->
      <groupId>org.hdrhistogram</groupId>
      <artifactId>HdrHistogram</artifactId>
      <version>2.1.10</version>
    </dependency>

    <dependency>
      <groupId>io.vertx</groupId>
      <artifactId>vertx-core</artifactId>
    </dependency>
    <dependency>
      <groupId>io.vertx</groupId>
      <artifactId>vertx-codegen</artifactId>
      <optional>true</optional>
    </dependency>
    <dependency>
      <groupId>io.vertx</groupId>
      <artifactId>vertx-docgen</artifactId>
      <optional>true</optional>
    </dependency>

    <!-- For tests and examples -->
    <dependency>
      <groupId>com.netflix.hystrix</groupId>
      <artifactId>hystrix-core</artifactId>
      <version>${hystrix.version}</version>
      <scope>provided</scope>
      <optional>true</optional>
    </dependency>

    <dependency>
      <groupId>com.jayway.restassured</groupId>
      <artifactId>rest-assured</artifactId>
      <version>2.8.0</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.assertj</groupId>
      <artifactId>assertj-core</artifactId>
      <version>3.3.0</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.jayway.awaitility</groupId>
      <artifactId>awaitility</artifactId>
      <version>1.7.0</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>com.github.tomakehurst</groupId>
      <artifactId>wiremock</artifactId>
      <version>2.2.1</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>io.vertx</groupId>
      <artifactId>vertx-unit</artifactId>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-jdk14</artifactId>
      <version>1.7.30</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>