maven transitive-dependency spring-boot-starter-parent

How to use dependencies from spring-boot-starter-parent?

I have a Spring Boot application using spring-boot-starter-parent 2.5.4:

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.5.4</version>
</parent>

<groupId>my.group</groupId>
<artifactId>myAtifactId</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>MyName</name>

I can see at Maven spring-boot-starter-parent 2.5.4

that it brings some dependencies I could use. Hence, I want to clean up dependencies added manually to the POM.

I removed some of those manually added dependencies like assertJ...and it works but when I remove Lombok or Awaitility, for instance, the mvn install fails. Why does this happen? If I add the dependency again (even without version) mvn install succeeds again. Isn't it possible to remove all dependencies added manually to the POM which are provided transitively by spring-boot-starter-parent?

Using mvn dependency:tree I can see that asserts-core comes with version 3.19.0 with scope test as described on MVNrepository. Lombok comes with version 1.18.20 with scope provided as described on MVNrepository. ...but when I remove this form my POM:

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
<!--    <version>${lombok.version}</version>-->
        <scope>provided</scope>
    </dependency>

...the mvn install fails:

.
.
.
constituent[42]: file:/Applications/IntelliJ%20IDEA.app/Contents/plugins/maven/lib/maven3/lib/maven-plugin-api-3.8.1.jar
---------------------------------------------------
Exception in thread "main" java.lang.AssertionError
    at jdk.compiler/com.sun.tools.javac.util.Assert.error(Assert.java:155)
    at jdk.compiler/com.sun.tools.javac.util.Assert.check(Assert.java:46)
    at jdk.compiler/com.sun.tools.javac.comp.Modules.enter(Modules.java:247)
    at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.readSourceFile(JavaCompiler.java:837)
    at jdk.compiler/com.sun.tools.javac.processing.JavacProcessingEnvironment$ImplicitCompleter.complete(JavacProcessingEnvironment.java:1530)
    at jdk.compiler/com.sun.tools.javac.code.Symbol.complete(Symbol.java:642)
    at jdk.compiler/com.sun.tools.javac.code.Symbol$ClassSymbol.complete(Symbol.java:1326)
    at jdk.compiler/com.sun.tools.javac.code.Type$ClassType.complete(Type.java:1140)
    at jdk.compiler/com.sun.tools.javac.code.Type$ClassType.getTypeArguments(Type.java:1066)
    at jdk.compiler/com.sun.tools.javac.code.Printer.visitClassType(Printer.java:237)
    at jdk.compiler/com.sun.tools.javac.code.Printer.visitClassType(Printer.java:52)
    at jdk.compiler/com.sun.tools.javac.code.Type$ClassType.accept(Type.java:993)
    at jdk.compiler/com.sun.tools.javac.code.Printer.visit(Printer.java:136)
    at jdk.compiler/com.sun.tools.javac.util.AbstractDiagnosticFormatter.formatArgument(AbstractDiagnosticFormatter.java:199)
    at jdk.compiler/com.sun.tools.javac.util.AbstractDiagnosticFormatter.formatArguments(AbstractDiagnosticFormatter.java:167)
    at jdk.compiler/com.sun.tools.javac.util.BasicDiagnosticFormatter.formatMessage(BasicDiagnosticFormatter.java:111)
    at jdk.compiler/com.sun.tools.javac.util.BasicDiagnosticFormatter.formatMessage(BasicDiagnosticFormatter.java:67)
    at jdk.compiler/com.sun.tools.javac.util.AbstractDiagnosticFormatter.formatArgument(AbstractDiagnosticFormatter.java:185)
    at jdk.compiler/com.sun.tools.javac.util.AbstractDiagnosticFormatter.formatArguments(AbstractDiagnosticFormatter.java:167)
    at jdk.compiler/com.sun.tools.javac.util.BasicDiagnosticFormatter.formatMessage(BasicDiagnosticFormatter.java:111)
    at jdk.compiler/com.sun.tools.javac.util.BasicDiagnosticFormatter.formatMessage(BasicDiagnosticFormatter.java:67)
    at jdk.compiler/com.sun.tools.javac.util.JCDiagnostic.getMessage(JCDiagnostic.java:788)
    at jdk.compiler/com.sun.tools.javac.api.ClientCodeWrapper$DiagnosticSourceUnwrapper.getMessage(ClientCodeWrapper.java:799)
    at org.codehaus.plexus.compiler.javac.JavaxToolsCompiler.compileInProcess(JavaxToolsCompiler.java:131)
    at org.codehaus.plexus.compiler.javac.JavacCompiler.performCompile(JavacCompiler.java:174)
    at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:1134)
    at org.apache.maven.plugin.compiler.CompilerMojo.execute(CompilerMojo.java:187)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:957)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:289)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:193)
    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.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)
    at org.codehaus.classworlds.Launcher.main(Launcher.java:47)

Process finished with exit code 1

Solution

Okay...lessons learned by Maven dependencyManagement vs. dependencies Tags Dependency management is used in order to declare the dependencies in the POM file. This declaration is just an announcement, and it doesn't really add the dependency to the project. dependencyManagement is just a declaration, and it does not really add a dependency. The declared dependencies in this section must be later used by the dependencies tag. It is just the dependencies tag that causes real dependency to happen.