Describe the PR

• Add the versions. Always select the latest version as "default".
• Make the version name be required - empty version names are not allowed anymore
• Make sure for each PMD language, that the names are reused for the CPD language (e.g. Ecmascript / JavaScript)
• Make sure for each PMD language, that the same extensions are used for CPD language
• ❌ Change extension for pom to xml (refs [pom] Maven POM Rules don't check files named "pom.xml" #1540) - won't do with this PR
  • we probably have anyway some extension clashes, at least for CPD (cpp vs. objectivec)
  • it turns out, that correctly detect, that "pom.xml" has two languages associated,
    but we just use the first language:

    pmd/pmd-core/src/main/java/net/sourceforge/pmd/lang/document/FileCollector.java

    Lines 233 to 236 in de9d395

    	Language lang = languages.get(0);
    	if (languages.size() > 1) {
    	LOG.trace("File {} matches multiple languages ({}), selecting {}", file, languages, lang);
    	}

  • this results in identifying any xml file now as language "pom" - and we don't execute the XML rules anymore against this file...
• Update release notes (esp. ecmascript versions)

Related issues

• Fixes [core] Explicitly name all language versions #4120

Ready?

• Added unit tests for fixed bug/feature
• Passing all unit tests
• Complete build ./mvnw clean verify passes (checked automatically by github actions)
• Added (in-code) documentation (if needed)