Linkage Checker Enforcer Rule verifies that the transitive dependency tree of pom.xml does not have any linkage errors.

User documentation: Linkage Checker Enforcer Rule

For developers to debug the enforcer rule implementation, set the MAVEN_OPTS environment variable to wait for debuggers (suspend=y) before running mvn command.

$ export MAVEN_OPTS='-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005'
$ mvn verify
Listening for transport dt_socket at address: 5005

When you debug one of the integration tests in the "src/it" directory, check the build.log files in the enforcer-rules/target/it directory (run find enforcer-rules -name 'build.log'). The file is used in verification scripts and usually contains build errors.

If you want to attach a debugger, use the following command to specify the test case and to provide the debug parameter to Maven invoker plugin.

mvn install -Dmaven.test.skip -Dinvoker.test=bom-project-using-spring-repository \
    -Dinvoker.mavenOpts='-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005'

Then run remote debug to the port (5005) via your IDE.