Docker build error when trying to copy .cfg file into karaf etc/

build.log

sb@lorenzo:~/workspaces/ws02/sonar-collector/docker$ mvn clean install
[INFO] Scanning for projects...
[INFO] Inspecting build with total of 1 modules...
[INFO] Installing Nexus Staging features:
[INFO]   ... total of 1 executions of maven-deploy-plugin replaced with nexus-staging-maven-plugin
[INFO] 
[INFO] -------------< no.priv.bang.sonar.sonar-collector:docker >--------------
[INFO] Building sonar-collector docker image 1.5.0-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO] 
[INFO] --- maven-clean-plugin:3.1.0:clean (default-clean) @ docker ---
[INFO] Deleting /home/sb/workspaces/ws02/sonar-collector/docker/target
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ docker ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /home/sb/workspaces/ws02/sonar-collector/docker/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.1:compile (default-compile) @ docker ---
[INFO] No sources to compile
[INFO] 
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ docker ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /home/sb/workspaces/ws02/sonar-collector/docker/src/test/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.8.1:testCompile (default-testCompile) @ docker ---
[INFO] No sources to compile
[INFO] 
[INFO] --- maven-surefire-plugin:2.22.2:test (default-test) @ docker ---
[INFO] No tests to run.
[INFO] 
[INFO] --- maven-jar-plugin:3.2.0:jar (default-jar) @ docker ---
[WARNING] JAR will be empty - no content was marked for inclusion!
[INFO] Building jar: /home/sb/workspaces/ws02/sonar-collector/docker/target/docker-1.5.0-SNAPSHOT.jar
[INFO] 
[INFO] >>> maven-source-plugin:2.4:jar (attach-sources) > generate-sources @ docker >>>
[INFO] 
[INFO] <<< maven-source-plugin:2.4:jar (attach-sources) < generate-sources @ docker <<<
[INFO] 
[INFO] 
[INFO] --- maven-source-plugin:2.4:jar (attach-sources) @ docker ---
[INFO] No sources in project. Archive not created.
[INFO] 
[INFO] --- maven-javadoc-plugin:3.1.1:jar (attach-javadocs) @ docker ---
[INFO] 
[INFO] --- docker-maven-plugin:1.2.2:build (build-image) @ docker ---
[INFO] Using authentication suppliers: [ConfigFileRegistryAuthSupplier]
[WARNING] Ignoring baseImage because dockerDirectory is set
[INFO] Copying docker/org.ops4j.datasource-sonar-collector.cfg -> /home/sb/workspaces/ws02/sonar-collector/docker/target/docker/org.ops4j.datasource-sonar-collector.cfg
[INFO] Copying docker/Dockerfile -> /home/sb/workspaces/ws02/sonar-collector/docker/target/docker/Dockerfile
[INFO] Building image steinarb/sonar-collector
Step 1/4 : FROM apache/karaf:4.3.2

 ---> 8dd7bd5bb021
Step 2/4 : ENV ORG_APACHE_KARAF_FEATURES_FEATURESREPOSITORIES='${featuresRepositories},mvn:no.priv.bang.sonar.sonar-collector/sonar-collector-webhook/LATEST/xml/features'

 ---> Using cache
 ---> 8210cda56107
Step 3/4 : ENV ORG_APACHE_KARAF_FEATURES_FEATURESBOOT='${featuresBoot},${env:JDBC_DRIVER_FEATURE:-postgresql},sonar-collector-webhook-with-postgresql'

 ---> Using cache
 ---> 2537b38ad255
Step 4/4 : COPY org.ops4j.datasource-sonar-collector.cfg /opt/apache-karaf/etc

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  3.405 s
[INFO] Finished at: 2021-06-20T09:07:06+02:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal com.spotify:docker-maven-plugin:1.2.2:build (build-image) on project docker: Exception caught: failed to copy files: lstat /var/lib/docker/overlay2/4b43399dd2a0d45f188577ee2b4272bfc54a4bc54ba776480b4b4fb2e3eca296/merged/opt/apache-karaf-4.3.2.tar.gz/etc: not a directory -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
sb@lorenzo:~/workspaces/ws02/sonar-collector/docker