private CustomAnalyzer.Builder withTokenizer(CustomAnalyzer.Builder builder,
                                                 LuceneAnalysisConfig.Analysis analysis) throws IOException {
        if (null == analysis) {
            // By default we use the "standard" tokenizer
            return builder.withTokenizer(STANDARD_TOKENIZER, new HashMap<>());
        }
        String tokenizerName = analysis.tokenizer().name();
        Map<String, String> conf = analysis.tokenizer().conf();
        return builder.withTokenizer(tokenizerName, asModifiable(conf));
    }
First, checks if a component is configured for a languageCode + StemMode.
Second, checks if Analyzer is configured only for a languageCode.
lucene-linguistics/src/main/java/com/yahoo/language/lucene/AnalyzerFactory.java