fess-crawler-parent/
├── fess-crawler/              # Core crawler framework
│   ├── client/               # Protocol clients (HTTP, FTP, SMB, etc.)
│   ├── extractor/           # Content extractors
│   ├── transformer/         # Data transformers
│   └── service/             # Core services
├── fess-crawler-lasta/       # LastaFlute DI integration
└── fess-crawler-opensearch/  # OpenSearch backend
```

### Key Components

                accessResult.setAccessResultData(null);
                try {
                    final Transformer transformer = ComponentUtil.getComponent(accessResultData.getTransformerName());
                    if (transformer == null) {
                        // no transformer
                        logger.warn("No transformer: {}", accessResultData.getTransformerName());
                        continue;
                    }

        TestTransformer transformer3 = new TestTransformer("transformer3");

        ResponseData responseData = new ResponseData();
        responseData.setUrl("http://example.com");

        ResultData result1 = transformer1.transform(responseData);
        ResultData result2 = transformer2.transform(responseData);
        ResultData result3 = transformer3.transform(responseData);

        TestTransformer transformer1 = new TestTransformer();
        NameTrackingTransformer transformer2 = new NameTrackingTransformer();

        transformer1.setName("transformer1");
        transformer2.setName("transformer2");

        assertEquals("transformer1", transformer1.getName());
        assertEquals("transformer2", transformer2.getName());

    final Multimap<K, V1> fromMultimap;
    final EntryTransformer<? super K, ? super V1, V2> transformer;

    TransformedEntriesMultimap(
        Multimap<K, V1> fromMultimap, EntryTransformer<? super K, ? super V1, V2> transformer) {
      this.fromMultimap = checkNotNull(fromMultimap);
      this.transformer = checkNotNull(transformer);
    }

    Collection<V2> transform(@ParametricNullness K key, Collection<V1> values) {

    final Multimap<K, V1> fromMultimap;
    final EntryTransformer<? super K, ? super V1, V2> transformer;

    TransformedEntriesMultimap(
        Multimap<K, V1> fromMultimap, EntryTransformer<? super K, ? super V1, V2> transformer) {
      this.fromMultimap = checkNotNull(fromMultimap);
      this.transformer = checkNotNull(transformer);
    }

    Collection<V2> transform(@ParametricNullness K key, Collection<V1> values) {

    }

    /**
     * Gets the transformer.
     *
     * @return the transformer
     */
    public Transformer getTransformer() {
        return transformer;
    }

    /**
     * Sets the transformer.
     *
     * @param transformer the transformer to set
     */
    public void setTransformer(final Transformer transformer) {
        this.transformer = transformer;
    }

    /**

        public XmlReaderRequestBuilder reader(Reader reader) {
            this.reader = reader;
            return this;
        }

        public XmlReaderRequestBuilder transformer(Transformer transformer) {
            this.transformer = transformer;
            return this;
        }

        public XmlReaderRequestBuilder strict(boolean strict) {
            this.strict = strict;
            return this;
        }

                        + responseProcessor + ", url: " + url);
            }
            final Transformer transformer = ((DefaultResponseProcessor) responseProcessor).getTransformer();
            final ResultData resultData = transformer.transform(responseData);
            final Object rawData = resultData.getRawData();
            if (rawData != null) {

                .<FileTransformer> singleton("fileTransformer", FileTransformer.class, transformer -> {
                    transformer.setName("fileTransformer");
                    transformer.setFeatureMap(featureMap);
                    transformer.setPropertyMap(propertyMap);
                    transformer.setChildUrlRuleMap(childUrlRuleMap);
                })