Spring Boot/Gradle/Querydsl project has the same dependency dependent on different versions of another dependency - spring-boot

Question

I am having problems adding Querydsl to my Spring Boot project. I have the following dependencies in my build.gradle file:
dependencies {
annotationProcessor 'com.querydsl:querydsl-apt:4.1.3:jpa'
annotationProcessor 'org.springframework.boot:spring-boot-starter-data-jpa'
implementation 'com.querydsl:querydsl-jpa:4.1.3'
implementation 'org.springframework.boot:spring-boot-starter-web'
implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
implementation 'org.springframework.boot:spring-boot-starter-security'
implementation 'org.springframework.cloud:spring-cloud-starter-netflix-eureka-client'
implementation 'org.springframework.security.oauth.boot:spring-security-oauth2-autoconfigure:2.1.3.RELEASE'
implementation 'org.springframework.cloud:spring-cloud-config-client:2.1.0.RELEASE'
implementation 'mysql:mysql-connector-java'
implementation 'io.springfox:springfox-swagger2:2.9.2'
implementation 'io.springfox:springfox-swagger-ui:2.9.2'
implementation 'io.springfox:springfox-bean-validators:2.9.2'
implementation group: 'org.latencyutils', name: 'LatencyUtils', version: '2.0.3'
testImplementation 'org.springframework.boot:spring-boot-starter-test'
testImplementation 'org.springframework.security:spring-security-test'
testImplementation 'junit:junit:4.12'
testImplementation 'org.mockito:mockito-inline:2.23.4'
}
The project builds fine, but when I run it, I get the following error:
An attempt was made to call the method com.google.common.collect.FluentIterable.concat(Ljava/lang/Iterable;Ljava/lang/Iterable;)Lcom/google/common/collect/FluentIterable; but it does not exist. Its class, com.google.common.collect.FluentIterable, is available from the following locations:
jar:file:/C:/Users/me/.gradle/caches/modules-2/files-2.1/com.google.guava/guava/18.0/cce0823396aa693798f8882e64213b1772032b09/guava-18.0.jar!/com/google/common/collect/FluentIterable.class
jar:file:/C:/Users/me/.gradle/caches/modules-2/files-2.1/com.google.guava/guava/20.0/89507701249388e1ed5ddcf8c41f4ce1be7831ef/guava-20.0.jar!/com/google/common/collect/FluentIterable.class
It was loaded from the following location:
file:/C:/Users/me/.gradle/caches/modules-2/files-2.1/com.google.guava/guava/18.0/cce0823396aa693798f8882e64213b1772032b09/guava-18.0.jar
Action:
Correct the classpath of your application so that it contains a single, compatible version of com.google.common.collect.FluentIterable
The Gradle window in IntelliJ shows the following:
Why does each instance of com.querydsl:querydsl-core:4.2.1 depend on a different version of guava?

Answer 1

The version 18.0 of Guava comes from querydsl and the 20.0 comes from spring-fox swagger.
spring-fox library expected that method of guava version 20.0 to be called. but called from 18.0. (because there are two guava library that has difference version in classpath)
you can use the following code to avoid conflict version of guava.
// QueryDsl
implementation("com.querydsl:querydsl-jpa:${querydslVersion}")
annotationProcessor("org.hibernate.javax.persistence:hibernate-jpa-2.1-api:1.0.2.Final")
annotationProcessor("com.querydsl:querydsl-apt:${querydslVersion}:jpa") {
exclude group: "come.google.guava"
}
annotationProcessor("com.google.guava:guava:20.0")