Show unused dependencies
mvn dependency:analyze
Show infos to one specific plugin (available goals with phases, etc.)
mvn help:describe -Dplugin=org.sonarsource.scanner.maven:sonar-maven-plugin -Ddetail
Show root of transitive dependency
mvn dependency:tree -Dincludes=org.apache.activemq:activemq-broker:jar:5.13.4 -Dverbose
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${project.basedir}- This references to the root folder of the module/project (the location where the current pom.xml file is located) -
${project.build.directory}- This represents by default the target folder. -
${project.build.outputDirectory}- This represents by default the target/classes folder. -
${project.build.testOutputDirectory}- This represents by default the target/test-classes folder. -
${project.build.sourceDirectory}- This represents by default the src/main/java folder. -
${project.build.testSourceDirectory}- This represents by default the src/test/java folder. -
${project.build.finalName}- This is by default defined as ${project.artifactId}-${project.version}. -
${project.version}- This can be used at locations where you have to write a literal version otherwise, in particular if you are in a multi-modules build for inter modules dependencies. -
${settings.localRepository}- which references the location of the local repository. This is by default ${home}/.m2/repository.
Those two elements are very much similar to object-oriented programming paradigm:
The <dependencyManagement> section only declares the dependencies and their details in the current project - the purpose is management of the details and re-use in other projects, either via inheritance (parent) or import (scope). This is like declaring a data type in program and make it available for use.
The <dependency> section defines the actual use of the dependencies in the project, optionally inherit the details (i.e., version, etc.) of the dependencies declared under the <dependencyManagment>. That's why you will have missing dependencies if you only put them in <dependencyManagement>. This is analogous to instantiating an variable instance of a data type in a program where it is needed.