code: private static void createLikelySubtags(TypeSpec.Builder type, Map<String, String> likelySubtags) {
      MethodSpec.Builder method = MethodSpec.methodBuilder("registerLikelySubtags")
          .addModifiers(PRIVATE, STATIC);
      
      for (Map.Entry<String, String> entry : likelySubtags.entrySet()) {
        method.addStatement("LIKELY_SUBTAGS_MAP.put($T.parse($S), $T.parse($S))",
            META_LOCALE, entry.getKey(), META_LOCALE, entry.getValue());
      }
      
      type.addMethod(method.build());
    }
docs: Create likely subtags mapping.