Deploy to Maven Central from a Gitlab CI workflow - gitlab-ci

Question

I maintain a few Java library projects on GitLab, which I build with a GitLab CI workflow and currently deploy to a GitLab Maven repository. Now I would like to deploy them to Maven Central instead, but have been unable to find any tutorials, examples or boilerplate code for doing so.
My current .gitlab-ci.yml looks like this:
Dorg.slf4j.simpleLogger.log.org.apache.maven.cli.transfer.Slf4jMavenTransferListener=WARN -Dorg.slf4j.simpleLogger.showDateTime=true -Djava.awt.headless=true"
MAVEN_CLI_OPTS: "--batch-mode --errors --fail-at-end --show-version -DinstallAtEnd=true -DdeployAtEnd=true"
image: maven:3.6.3-openjdk-8
cache:
key: "$CI_JOB_NAME"
paths:
- .m2/repository
- public
.verify: &verify
stage: test
script:
- 'mvn $MAVEN_CLI_OPTS verify'
except:
- master
- dev
verify:jdk8:
<<: *verify
# Deploy to GitLab's Maven Repository for `master` and `dev` branch
deploy:jdk8:
stage: deploy
script:
- if [ ! -f ci_settings.xml ];
then echo "CI settings missing\! If deploying to GitLab Maven Repository, please see https://docs.gitlab.com/ee/user/project/packages/maven_repository.html#creating-maven-packages-with-gitlab-cicd for instructions.";
fi
- 'mvn $MAVEN_CLI_OPTS deploy -s ci_settings.xml'
only:
- master
- dev
# Deploy Javadoc to GitLab Pages
pages:
stage: deploy
script:
- 'mvn javadoc:javadoc -DadditionalJOption=-Xdoclint:none'
- if [ -e public/javadoc/$CI_COMMIT_REF_NAME ];
then rm -Rf public/javadoc/$CI_COMMIT_REF_NAME ;
fi
- 'mkdir -p public/javadoc/$CI_COMMIT_REF_NAME'
- 'cp -r target/site/apidocs/* public/javadoc/$CI_COMMIT_REF_NAME/'
artifacts:
paths:
- public
only:
- master
- dev
The closest I found was an instruction on deploying to Artifactory, but nothing about Maven Central. What is the procedure for Maven Central?