Running `publishToMavenLocal` reports warnings

[StefMa]

One javadoc warning:

> Task :javadoc
/path/wrapper-upgrade-gradle-plugin/src/main/java/org/gradle/wrapperupgrade/WrapperUpgradeDomainObject.java:46: warning: no @param for action
    public void options(Action<Options> action) {
                ^
1 warning

And one publishing warning:

> Task :publishPluginMavenPublicationToMavenLocal
Multiple publications with coordinates 'org.gradle:wrapper-upgrade-gradle-plugin:99.99.99' are published to repository 'mavenLocal'. The publications 'mavenJava' in root project 'wrapper-upgrade-gradle-plugin' and 'pluginMaven' in root project 'wrapper-upgrade-gradle-plugin' will overwrite each other!