Issues of integrating flowable with mongodb

I followed the mongodb & flowable tutorial, my flowable engine version is 6.6, spring version is 2.3.3.

Here is my pom.xml.

<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
    	        <version>2.3.3.RELEASE</version>		
		<relativePath/>  
	</parent>

	<groupId>com.example</groupId>
	<artifactId>demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>demo</name>
	<description>Demo project for Spring Boot</description>
	<properties>
		<java.version>11</java.version>
               <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
               <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
               <mongodb.version>3.6.0-beta1</mongodb.version>		
	</properties>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>

		<dependency>
			<groupId>org.flowable</groupId>
			<artifactId>flowable-engine</artifactId>
			<version>6.6.0</version>
		</dependency>
		<dependency>
			<groupId>org.flowable</groupId>
			<artifactId>flowable-process-engine-mongodb</artifactId>
			<version>6.4.0.alpha1</version>
		</dependency>
        <dependency>
            <groupId>org.mongodb</groupId>
            <artifactId>mongodb-driver</artifactId>
            <version>3.12.7</version>
        </dependency>

	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>

In the springboot application

@Bean
public ProcessEngineConfiguration processEngineConfiguration() {
    return new MongoDbProcessEngineConfiguration()
        .setConnectionUrl("localhost:27017")
        .setDisableIdmEngine(true)
      
  .setDatabaseSchemaUpdate(MongoDbProcessEngineConfiguration.DB_SCHEMA_UPDATE_TRUE)
        .setHistoryLevel(HistoryLevel.AUDIT);
}

@Bean
public ProcessEngine processEngine() {
    return processEngineConfiguration().buildProcessEngine();
}

when running the spring boot, some errors appeared

2021-05-27 12:05:03 [main] WARN  org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext -Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'expenseController': Unsatisfied dependency expressed through field 'runtimeService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'runtimeServiceBean' defined in class path resource [org/flowable/spring/boot/ProcessEngineServicesAutoConfiguration.class]: Unsatisfied dependency expressed through method 'runtimeServiceBean' parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processEngine' defined in com.example.demo.DemoApplication: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.flowable.engine.ProcessEngine]: Factory method 'processEngine' threw exception; nested exception is java.lang.NoClassDefFoundError: com/mongodb/MongoClientSettings
2021-05-27 12:05:03 [main] ERROR org.springframework.boot.SpringApplication -Application run failed
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'expenseController': Unsatisfied dependency expressed through field 'runtimeService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'runtimeServiceBean' defined in class path resource [org/flowable/spring/boot/ProcessEngineServicesAutoConfiguration.class]: Unsatisfied dependency expressed through method 'runtimeServiceBean' parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processEngine' defined in com.example.demo.DemoApplication: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.flowable.engine.ProcessEngine]: Factory method 'processEngine' threw exception; nested exception is java.lang.NoClassDefFoundError: com/mongodb/MongoClientSettings
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:643)
        at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:130)
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1420)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:593)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:516)
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:324)
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226)
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:897)
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:879)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:551)
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143)
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758)
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750)
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:315)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226)
        at com.example.demo.DemoApplication.main(DemoApplication.java:42)
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'runtimeServiceBean' defined in class path resource [org/flowable/spring/boot/ProcessEngineServicesAutoConfiguration.class]: Unsatisfied dependency expressed through method 'runtimeServiceBean' parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processEngine' defined in com.example.demo.DemoApplication: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.flowable.engine.ProcessEngine]: Factory method 'processEngine' threw exception; nested exception is java.lang.NoClassDefFoundError: com/mongodb/MongoClientSettings
        at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:797)
        at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:538)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1336)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1176)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:556)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:516)
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:324)
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226)
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
        at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1307)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1227)
        at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640)
        ... 20 common frames omitted
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processEngine' defined in com.example.demo.DemoApplication: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.flowable.engine.ProcessEngine]: Factory method 'processEngine' threw exception; nested exception is java.lang.NoClassDefFoundError: com/mongodb/MongoClientSettings
        at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:655)
        at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:483)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1336)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1176)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:556)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:516)
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:324)
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226)
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202)
        at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1307)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1227)
        at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:884)
        at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:788)
        ... 33 common frames omitted
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.flowable.engine.ProcessEngine]: Factory method 'processEngine' threw exception; nested exception is java.lang.NoClassDefFoundError: com/mongodb/MongoClientSettings
        at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185)
        at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:650)
        ... 47 common frames omitted
Caused by: java.lang.NoClassDefFoundError: com/mongodb/MongoClientSettings
        at com.mongodb.MongoClient.getDefaultCodecRegistry(MongoClient.java:111)
        at com.mongodb.MongoClientOptions$Builder.<init>(MongoClientOptions.java:1039)
        at com.mongodb.MongoClientOptions.builder(MongoClientOptions.java:214)
        at org.flowable.mongodb.cfg.MongoDbProcessEngineConfiguration.initNonRelationalDataSource(MongoDbProcessEngineConfiguration.java:86)
        at org.flowable.engine.impl.cfg.ProcessEngineConfigurationImpl.init(ProcessEngineConfigurationImpl.java:1027)
        at org.flowable.engine.impl.cfg.ProcessEngineConfigurationImpl.buildProcessEngine(ProcessEngineConfigurationImpl.java:980)
        at com.example.demo.DemoApplication.processEngine(DemoApplication.java:37)
        at com.example.demo.DemoApplication$$EnhancerBySpringCGLIB$$551d797e.CGLIB$processEngine$1(<generated>)
        at com.example.demo.DemoApplication$$EnhancerBySpringCGLIB$$551d797e$$FastClassBySpringCGLIB$$46f882e9.invoke(<generated>)
        at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244)
        at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:331)
        at com.example.demo.DemoApplication$$EnhancerBySpringCGLIB$$551d797e.processEngine(<generated>)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154)
        ... 48 common frames omitted
Caused by: java.lang.ClassNotFoundException: com.mongodb.MongoClientSettings
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)

i guess it might be the problem with the configuration of spring, flowable and mongodb version. Anyone knows what is the problem and how to solve it?

thanks