Maven dependency BOM camel-spring-boot-bom not working with Gradle

Question

I'm trying to get the Apache Camel Spring Boot BOM working. However, it does neither work by specifying it as a dependency with

dependencies {
   implementation platform("org.apache.camel.springboot:camel-spring-boot-bom:${camelVersion}")
   .
   .
   .
}

or

dependencies {
   implementation "org.apache.camel.springboot:camel-spring-boot-bom:${camelVersion}"
   .
   .
   .
}

Nor by using the dependencyManagement imports alongside other that are working

dependencyManagement {
  imports {
    mavenBom SpringBootPlugin.BOM_COORDINATES
    mavenBom "org.junit:junit-bom:${junitVersion}"
    mavenBom "org.apache.camel:camel-bom:${camelVersion}"
    mavenBom "io.github.openfeign:feign-bom:${feignVersion}"
    mavenBom "org.apache.camel.springboot:camel-spring-boot-bom:${camelVersion}"
    mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
}

together with the actual dependencies (without versions specified explicitly)

implementation "org.apache.camel.springboot:camel-csv-starter"
implementation "org.apache.camel.springboot:camel-rest-starter"
implementation "org.apache.camel.springboot:camel-seda-starter"
implementation "org.apache.camel.springboot:camel-direct-starter"
implementation "org.apache.camel.springboot:camel-jackson-starter"
implementation "org.apache.camel.springboot:camel-servlet-starter"
implementation "org.apache.camel.springboot:camel-zipfile-starter"
implementation "org.apache.camel.springboot:camel-resilience4j-starter"
implementation "org.apache.camel.springboot:camel-rest-openapi-starter"
implementation "org.apache.camel.springboot:camel-platform-http-starter"

implementation "org.apache.camel.springboot:camel-spring-boot-starter"
implementation "org.apache.camel.springboot:camel-platform-http-starter"
implementation "org.apache.camel.springboot:camel-spring-boot-dependencies"

and in both ways I'm getting

> Could not resolve all dependencies for configuration ':my-project:compileClasspath'.
  The project declares repositories, effectively ignoring the repositories you have declared in the settings.
  You can figure out how project repositories are declared by configuring your build to fail on project repositories.
  See https://docs.gradle.org/7.5.1/userguide/declaring_repositories.html#sub:fail_build_on_project_repositories for details.
   > Could not find org.apache.camel.springboot:camel-spring-boot-dependencies:.
     Required by:
         project :my-project

while directly using version numbers in individual dependencies like

dependencies {
   implementation "org.apache.camel.springboot:camel-spring-boot-starter:${camelVersion}"
}

is perfectly working.

Why does it seem the Spring Boot Camel BOM is working "differently" than the other dependencies and how do I get it working?

Answer 1

The bom 'dependency' is actually just a reference for which version to use for any dependency you bring in within dependencies{ } specified in the bom (including transitive). So for example:

dependencies {
   implementation "org.apache.camel.springboot:camel-spring-boot-starter"
}
dependencyManagement {
  imports {
    mavenBom "org.apache.camel.springboot:camel-spring-boot-bom:${camelVersion}"
}

This code above if you see, camel-spring-boot-starter does not have a version specified to it, but it is still able to resolve because the version is specified within the bom file of camel-spring-boot-bom:${camelVersion}.

And just in case for reference here you can find the dependencies and the version your dependencies will resolve with, for example version 3.20.0 of bom: https://mvnrepository.com/artifact/org.apache.camel.springboot/camel-spring-boot-bom/3.20.0

Answer 2

I mistakenly had a second BOM org.apache.camel.springboot:camel-spring-boot-dependencies listed as a dependency, which caused the problem when I was removing the version number.

I've removed that from the dependencies now and used it as the BOM, as it fits my needs better.

According to the docs:

There is a curated camel-spring-boot-dependencies which is a generated BOM that has adjusted the JARs that both Spring Boot and Apache Camel may use to use single shared version that will not conflict. This BOM is what is used to test camel-spring-boot itself. However Spring Boot users may want to use pure Camel dependencies and hence why you can use camel-spring-boot-bom that only has the Camel starter JARs as managed dependencies. This may lead to a classpath conflict if a 3rd party JAR from Spring Boot is not compatible with a Camel component.

https://camel.apache.org/camel-spring-boot/3.19.x/index.html#_camel_spring_boot_bom_vs_camel_spring_boot_dependencies_bom