Maven dependency conflict: Swagger2 version 2.9.2 and Hateoas (with Spring :- spring-boot-starter-parent version 2.2.6.RELEASE)

Question

I am trying to set a Spring Boot applications with Swagger2 and hateoas dependency in the pom.xml file of a spring project but I am getting the below error while starting the application.

**

Error Stack

2020-05-03 18:29:55.906 DEBUG 13184 --- [  restartedMain] .c.l.ClasspathLoggingApplicationListener : Application started with classpath: [file:/D:/My_Learnings/SpringBoot/IntellijProjects/restful-services/target/classes/]

      .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.2.6.RELEASE)



Exclusions:
-----------

    None


Unconditional classes:
----------------------

    org.springframework.boot.autoconfigure.context.ConfigurationPropertiesAutoConfiguration

    org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration

    org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration



2020-05-03 18:36:05.926 DEBUG 1900 --- [  restartedMain] o.s.b.d.LoggingFailureAnalysisReporter   : Application failed to start due to an exception

org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'org.springframework.plugin.core.PluginRegistry<org.springframework.hateoas.client.LinkDiscoverer, org.springframework.http.MediaType>' available: expected single matching bean but found 3: relProviderPluginRegistry,linkDiscovererRegistry,entityLinksPluginRegistry
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveNotUnique(DependencyDescriptor.java:220) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1268) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1210) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:885) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:789) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:539) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:882) ~[spring-beans-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.5.RELEASE.jar:5.2.5.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.6.RELEASE.jar:2.2.6.RELEASE]
    at code.muffy.spring.restfulservices.rest_services.RestfulServicesApplication.main(RestfulServicesApplication.java:18) [classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_241]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_241]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_241]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_241]
    at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.2.6.RELEASE.jar:2.2.6.RELEASE]

2020-05-03 18:36:05.926 ERROR 1900 --- [  restartedMain] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 0 of method linkDiscoverers in org.springframework.hateoas.config.HateoasConfiguration required a single bean, but 3 were found:
    - relProviderPluginRegistry: defined by method 'relProviderPluginRegistry' in class path resource [org/springframework/hateoas/config/HateoasConfiguration.class]
    - linkDiscovererRegistry: defined in null
    - entityLinksPluginRegistry: defined by method 'entityLinksPluginRegistry' in class path resource [org/springframework/hateoas/config/WebMvcEntityLinksConfiguration.class]


Action:

Consider marking one of the beans as @Primary, updating the consumer to accept multiple beans, or using @Qualifier to identify the bean that should be consumed

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As per the error stack, I thought this might be because of adding hateoas dependency so I tried removing that dependency and it ran fine. But I have to use both hateoas and Swagger2 in my project. I am new to spring boot, can anyone please suggest to me how I can solve this issue while having both the dependencies present in the pom.xml file. Is spring trying to create some beans from these dependencies and getting confused because multiple beans are being created for the same class? I am not sure of the problem, can anyone give their insight and help me resolve this? Or is there any version compatibility issue between the dependencies?

Maven POM.XML:-

<?xml version="1.0" encoding="UTF-8"?>
<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>2.2.6.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>code.muffy.spring</groupId>
<artifactId>restful-services</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>restful-services</name>
<description>Project for Spring Boot (Rest Services)</description>

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

    <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.dataformat/jackson-dataformat-xml -->
    <dependency>
        <groupId>com.fasterxml.jackson.dataformat</groupId>
        <artifactId>jackson-dataformat-xml</artifactId>
    </dependency>
    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-swagger2</artifactId>
        <version>2.9.2</version>
    </dependency>
    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-swagger-ui</artifactId>
        <version>2.9.2</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-hateoas</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
        <exclusions>
            <exclusion>
                <groupId>org.junit.vintage</groupId>
                <artifactId>junit-vintage-engine</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
</dependencies>

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

I am also sharing the code snippet just in case it might help :-

UserResource.java ----

@RestController
public class UserResource {

@Autowired
private UserDao userDao;

@GetMapping("/users")
public List<User> retrieveAllUsers() {
    return userDao.findAll();
}

@PostMapping("/users")
public ResponseEntity<Object> saveUser(@RequestBody User user) {
    userDao.save(user);
    URI location = ServletUriComponentsBuilder
            .fromCurrentRequest()
            .path("/{id}")
            .buildAndExpand(user.getId())
            .toUri();
    return ResponseEntity.created(location).build();
}

@GetMapping("/user/{id}")
public EntityModel<User> findUser(@PathVariable int id) throws Exception {
    User user = userDao.findOne(id);
    EntityModel<User> resource = new EntityModel<>(user);
    Link link = linkTo(methodOn(this.getClass()).retrieveAllUsers())
            .withRel("all-users");
    resource.add(link);
    return resource;
}

@DeleteMapping("/user/{id}")
public void deleteUser(@PathVariable int id) throws Exception {
    userDao.deleteById(id);
}

}

I have excluded adding CONDITION_REPORT from the debug log. It's exceeding stackoverflow maximum characters for a post. Please let me know if you require that also. I will try to attach it in the comments.

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